Non-erythroid protein 4.1R (4.1R) consists of a complex family of isoforms. We have shown that 4.1R isoforms localize at the mitotic spindle/spindle poles and associate in a complex with the mitotic-spindle organization proteins Nuclear Mitotic Apparatus protein (NuMA), dynein, and dynactin. We addressed the mitotic function of 4.1R by investigating its association with microtubules, the main component of the mitotic spindles, and its role in mitotic aster assembly in vitro. 4.1R appears to partially co-localize with microtubules throughout the mitotic stages of the cell cycle. In vitro sedimentation assays showed that 4.1R isoforms directly interact with microtubules. Glutathione S-transferase (GST) pull-down assays using GST-4.1R fusions and mitotic cell extracts further showed that the association of 4.1R with tubulin results from both the membrane-binding domain and C-terminal domain of 4.1R. Moreover, 4.1R, but not actin, is a mitotic microtubule-associated protein; 4.1R associates with microtubules in the microtubule pellet of the mitotic asters assembled in mammalian cell-free mitotic extract. The organization of microtubules into asters depends on 4.1R in that immunodepletion of 4.1R from the extract resulted in randomly dispersed microtubules. Furthermore, adding a 135-kDa recombinant 4.1R reconstituted the mitotic asters. Finally, we demonstrated that a mitotic 4.1R isoform appears to form a complex in vivo with tubulin and NuMA in highly synchronized mitotic HeLa extracts. Our results suggest that a 135-kDa non-erythroid 4.1R is important to cell division, because it participates in the formation of mitotic spindles and spindle poles through its interaction with mitotic microtubules. Non-erythroid protein 4.1R (4.1R) consists of a complex family of isoforms. We have shown that 4.1R isoforms localize at the mitotic spindle/spindle poles and associate in a complex with the mitotic-spindle organization proteins Nuclear Mitotic Apparatus protein (NuMA), dynein, and dynactin. We addressed the mitotic function of 4.1R by investigating its association with microtubules, the main component of the mitotic spindles, and its role in mitotic aster assembly in vitro. 4.1R appears to partially co-localize with microtubules throughout the mitotic stages of the cell cycle. In vitro sedimentation assays showed that 4.1R isoforms directly interact with microtubules. Glutathione S-transferase (GST) pull-down assays using GST-4.1R fusions and mitotic cell extracts further showed that the association of 4.1R with tubulin results from both the membrane-binding domain and C-terminal domain of 4.1R. Moreover, 4.1R, but not actin, is a mitotic microtubule-associated protein; 4.1R associates with microtubules in the microtubule pellet of the mitotic asters assembled in mammalian cell-free mitotic extract. The organization of microtubules into asters depends on 4.1R in that immunodepletion of 4.1R from the extract resulted in randomly dispersed microtubules. Furthermore, adding a 135-kDa recombinant 4.1R reconstituted the mitotic asters. Finally, we demonstrated that a mitotic 4.1R isoform appears to form a complex in vivo with tubulin and NuMA in highly synchronized mitotic HeLa extracts. Our results suggest that a 135-kDa non-erythroid 4.1R is important to cell division, because it participates in the formation of mitotic spindles and spindle poles through its interaction with mitotic microtubules. Protein 4.1R is an 80-kDa structural component of the red blood cell cytoskeleton. 4.1R is critical to the formation of the spectrin/actin/4.1R junctional complex, whose integrity is vital for the mechanical stability and elasticity of the red blood cells (reviewed in Ref. 1.Benz, E. J., Jr. (1994) in The Molecular Basis of Blood Diseases (Stamatoyannopoulos, G., Neinhuis, A. W., Majerus, P., Varmus, H., eds) 2nd Ed., pp. 257–292Google Scholar). The 80-kDa 4.1R of mature red blood cells is the prototype of a large array of 4.1R isoforms arising from a single gene by utilizing different promoters (2Parra M.K. Gee S.L. Koury M.J. Mohandas N. Conboy J.G. Blood. 2003; 101: 4164-4171Crossref PubMed Scopus (30) Google Scholar), alternative mRNA splicing (3Conboy J.G. Chan J. Mohandas N. Kan Y.W. Proc. Natl. Acad. Sci. U. S. A. 1988; 85: 9062-9065Crossref PubMed Scopus (97) Google Scholar, 4Tang T.K. Quin Z. Marchesi V.T. Benz Jr., E.J. J. Cell Biol. 1990; 110: 617-624Crossref PubMed Scopus (89) Google Scholar), two translation initiation sites (5Huang S.C. Baklouti F. Tang T.K. Benz Jr., E.J. Trans. Assoc. Am. Phys. 1992; CV: 165-171Google Scholar, 6Chasis J.A. Coulombel L. McGee S. Lee G. Tchernia G. Conboy J.G. Mohandas N. Blood. 1996; 87: 5324-5331Crossref PubMed Google Scholar), and post-translational modifications (7Subrahmanyam G. Bertics P.J. Anderson R.A. Proc. Natl. Acad. Sci. U. S. A. 1991; 88: 5222-5226Crossref PubMed Scopus (55) Google Scholar). Three homologues of 4.1R, namely 4.1G, 4.1N, and 4.1B, have been identified (8Walensky L.D. Blackshaw S. Liao D. Watkins C.C. Weier H.U. Parra M. Huganir R.L. Conboy J.G. Mohandas N. Snyder S.H. J. Neurosci. 1999; 19: 6457-6467Crossref PubMed Google Scholar, 9Ohara R. Yamakawa H. Nakayama M. Yuasa S. Ohara O. Brain Res. Dev. Brain Res. 1999; 117: 127-138Crossref PubMed Scopus (18) Google Scholar, 10Tran Y.K. Bogler O. Gorse K.M. Wieland I. Green M.R. Newahsm I.F. Cancer Res. 1999; 59: 35-43PubMed Google Scholar, 11Parra M. Gascard P. Walensky L.D. Gimm J.A. Blackshaw S. Chan N. Takakuwa Y. Berger T. Lee G. Chasis J.A. Snyder S.H. Mohandas N. Conboy J.G. J. Biol. Chem. 2000; 275: 3247-3255Abstract Full Text Full Text PDF PubMed Scopus (118) Google Scholar). They share a common structural organization with 4.1R: highly conserved protein interaction domains (the 30-kDa membrane-binding domain (MBD 1The abbreviations used membrane-binding Nuclear Mitotic Apparatus protein; C-terminal the domain and the to C-terminal domain with The domain and in the domain to 4.1R. 4.1R in non-erythroid cells by family alternative splicing is a protein family (3Conboy J.G. Chan J. Mohandas N. Kan Y.W. Proc. Natl. Acad. Sci. U. S. A. 1988; 85: 9062-9065Crossref PubMed Scopus (97) Google Scholar, 4Tang T.K. Quin Z. Marchesi V.T. Benz Jr., E.J. J. Cell Biol. 1990; 110: 617-624Crossref PubMed Scopus (89) Google Scholar, M. M. F. S. M. Walensky L.D. S. Chasis J.A. Conboy J.G. Mohandas N. Gascard P. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar). isoforms of 4.1R in non-erythroid cell The and of proteins in to cell and 4.1R isoforms to critical of important 4.1R isoforms have been shown to interact with microtubules in cells I. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar), the of the in A. S.C. Benz Jr., E.J. Biol. 2000; PubMed Scopus Google Scholar), and the proteins in cells S.C. Benz Jr., E.J. J. Biol. Chem. 2000; 275: Full Text Full Text PDF PubMed Scopus Google Scholar). 4.1R isoforms have been shown to the of the G. M.J. I. J. PubMed Scopus Google Scholar, S. Gascard P. S. Mohandas N. Chasis J.A. J. Cell Biol. PubMed Scopus Google and in splicing M.J. I. J. Cell Sci. 110: Google Scholar). 4.1R is the cell it in the and of cells and to the spindle poles the in G. M.J. I. J. PubMed Scopus Google Scholar, S. Gascard P. S. Mohandas N. Chasis J.A. J. Cell Biol. PubMed Scopus Google Scholar, Chasis J.A. Mohandas N. G. S. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar, S.C. Snyder M. Marchesi V.T. Benz Jr., E.J. J. Cell Biol. 1999; PubMed Scopus Google Scholar). In with the in the cell by the the of 4.1R to the mitotic spindle and spindle poles is by a that at and sites by E. S. I. D. H. T. and E. J. Jr., We S.C. Snyder M. Marchesi V.T. Benz Jr., E.J. J. Cell Biol. 1999; PubMed Scopus Google showed that a 135-kDa 4.1R isoform in its association with the proteins dynein, and to the organization of spindle poles and of the to the spindle A. L.D. 1996; 87: Full Text Full Text PDF PubMed Scopus Google Scholar). we that 4.1R an important role in mitotic spindle and spindle cell is the of an of microtubules into a spindle that the of both and in the spindle that the at the poles the the cell PubMed Scopus Google Scholar, U. J. Cell Biol. PubMed Scopus Google Scholar). have to the and in microtubules into spindles (reviewed in Ref. 2000; PubMed Scopus Google Scholar). In the of microtubule and the microtubule from not to spindle poles T. J. Cell Biol. PubMed Scopus Google Scholar). The organization of microtubules into spindles is by the interaction of microtubules and microtubule with proteins that microtubule proteins P. J. Cell Biol. PubMed Scopus Google Scholar), J. Cell Biol. 1999; PubMed Scopus Google Scholar), J. Cell Sci. PubMed Google Scholar), L. A. G. J. Cell Biol. 1999; PubMed Scopus Google Scholar), A. J. Biol. Chem. 2000; 275: Full Text Full Text PDF PubMed Scopus Google Scholar), J.A. T. S. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar), and Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar), the structural protein NuMA T. A. J. Cell Biol. PubMed Scopus Google in microtubules at spindle for proteins that associate with spindle poles and for the proteins that of the spindle In we the association of 4.1R with microtubules, the main component of the mitotic spindles, and the role of 4.1R in mitotic aster assembly in vitro. We that 4.1R is a mitotic microtubule-associated protein and that 4.1R is critical to the organization of microtubules into asters in HeLa mitotic extracts. Our suggest that a non-erythroid 135-kDa 4.1R is an important component of cell by in the formation of mitotic spindles and spindle poles through its interaction with mitotic microtubules. to of of 4.1R and the recombinant of 4.1R S.C. Snyder M. Marchesi V.T. Benz Jr., E.J. J. Cell Biol. 1999; PubMed Scopus Google Scholar). The on using the to the used for The from the with with and into from and from (the of from and Protein by of 4.1R T.K. I. Marchesi V.T. Benz Jr., E.J. Proc. Natl. Acad. Sci. U. S. A. 1988; 85: PubMed Scopus Google by using an and a The by a 4.1R F. S.C. Benz Jr., E.J. PubMed Scopus Google and into and sites of and its different domains in with at used to the with and and into The for of 4.1R domains and In recombinant 4.1R protein using with a the to the of the of the the of GST-4.1R to the the into for protein and of 4.1R in of at and the of 4.1R by at in of and The through a with The 4.1R and an 4.1R from the by a from to in the recombinant 4.1R using The protein using a In and microtubule using the Protein to the of and on the mitotic cell in with and The cell by with at for of recombinant and proteins to with of mitotic cell at for in with and with to the and of and GST-4.1R fusions used in the a with the of proteins with In Mitotic cells in with mitotic HeLa cells by of the cells at the of the cell by a J. M. Cell Scholar). in from the for and the mitotic by of of for The in vitro aster assembly using an T. J. Cell Biol. PubMed Scopus Google Scholar, A. J. Biol. Chem. 2000; 275: Full Text Full Text PDF PubMed Scopus Google Scholar). mitotic cells by and with for at with and at a of in and and the extract to at for at The and to and the of microtubule with and The with and and microtubule asters assembled by at for for The through in at for at to mitotic microtubule-associated proteins in the and pellet directly in for and HeLa mitotic extracts to of 4.1R to protein and with mitotic extracts for at The the and the and in to to the of of 4.1R and the of NuMA and tubulin in extracts. The to the in vitro aster assembly Mitotic recombinant to mitotic extracts and to an in vitro aster assembly and of 4.1R, and NuMA using HeLa mitotic extracts S.C. Snyder M. Marchesi V.T. Benz Jr., E.J. J. Cell Biol. 1999; PubMed Scopus Google Scholar). In mitotic HeLa cells in and in a The at for at and the with the with The for the of 4.1R, tubulin using its using the and the protein of by using the of for the and cells on and to S.C. Snyder M. Marchesi V.T. Benz Jr., E.J. J. Cell Biol. 1999; PubMed Scopus Google Scholar). Mitotic asters assembled in vitro on in and to T. J. Cell Biol. PubMed Scopus Google Scholar). The with an a using and using Protein 4.1R and the Cell S.C. Snyder M. Marchesi V.T. Benz Jr., E.J. J. Cell Biol. 1999; PubMed Scopus Google that a 135-kDa 4.1R isoform with NuMA and associates in a complex dynein, and dynactin. The complex is to localize to the spindle poles and to spindle microtubules A. L.D. 1996; 87: Full Text Full Text PDF PubMed Scopus Google Scholar). NuMA directly to tubulin and the spindle poles by to the microtubule at the poles L. A. J. Cell Sci. Google Scholar). NuMA and with both 4.1R and we the association of 4.1R with with to the mitotic we used to 4.1R and to at different stages of cell cycle. of HeLa cells that 4.1R throughout the but in the tubulin in the of 4.1R and tubulin in is the is by and red 4.1R and microtubules at the of the spindle poles throughout 4.1R and tubulin in a and at the spindle and spindle poles 4.1R in the in the tubulin with microtubules by with its not We the 4.1R in cells and cells in of in The the 4.1R shown in the results suggest that 4.1R partially and with tubulin in the of cells and in the spindle and spindle poles Protein 4.1R with in and in Mitotic of 4.1R and tubulin at the spindle and spindle poles of mitotic cells to mitotic 4.1R isoforms interact with microtubules. Our of 4.1R mRNA in HeLa that a 135-kDa isoform of the and is a isoform that is in mitotic directly with microtubules, we used recombinant protein and microtubules in microtubule sedimentation assays to the interaction and 80-kDa 4.1R isoform that been shown to interact with microtubules I. J. J. 1988; Google a microtubules with recombinant and through a and not to the pellet not both in the pellet with microtubules but not in the interaction with microtubules in vitro. interaction a to microtubules, not not the of the interaction 4.1R and tubulin in mitotic cells and to the domains of 4.1R for the we a pull-down using of mitotic HeLa We the and of 4.1R its domain and proteins with an of of the because of post-translational of the fusions and to and with of HeLa mitotic we used to the proteins for to with the in vitro sedimentation that tubulin with the and domains and tubulin that the and of 4.1R for its to tubulin in mitotic HeLa The the with mitotic tubulin in that not interact with we not of post-translational is in it appears that the at the not to the tubulin of 4.1R, because both the 80-kDa the and the 135-kDa with the of the to tubulin Protein 4.1R a of Mitotic in a Mitotic 4.1R an role in the mitotic spindle we 4.1R is a component of mitotic asters assembled in a in vitro mitotic aster assembly T. J. Cell Biol. PubMed Scopus Google Scholar, A. J. Biol. Chem. 2000; 275: Full Text Full Text PDF PubMed Scopus Google Scholar, Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). In to the complex interaction R. Parra M. Conboy J.G. Mohandas N. J. Cell Biol. PubMed Scopus (97) Google Scholar, A. Benz Jr., E.J. S.C. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar), 4.1R a interaction with R. Parra M. Conboy J.G. Mohandas N. J. Cell Biol. PubMed Scopus (97) Google Scholar, R. Parra M.K. Conboy J.G. Mohandas N. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google J.A. Mohandas N. PubMed Scopus Google Scholar). We and the interaction and 4.1R by the of to mitotic extracts to the assembly to with in the of in the HeLa mitotic extract. at for mitotic asters into in a that is by microtubule and structural Mitotic asters assembled in extract of microtubules in a array that NuMA at the T. J. Cell Biol. PubMed Scopus Google Scholar). with the of and T. A. J. Cell Biol. PubMed Scopus Google Scholar), the microtubules in in the of NuMA not at the in We the asters from the of the extract by through a for the sedimentation of microtubule asters with Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). a of 4.1R, but not actin, with and tubulin the proteins to associate with microtubules in the microtubule The of and the of the of in the pellet and the of 4.1R with results that 4.1R is a mitotic microtubule-associated The of the aster formation is the of both NuMA and tubulin from a form to an form T. A. J. Cell Biol. PubMed Scopus Google by the of NuMA and tubulin into the pellet of the is that is a the of the aster and the of aster We in the and the asters from extracts that assembly to we asters a In we a of asters the and shown in Protein 4.1R for Mitotic in the formation of mitotic microtubule asters in synchronized mitotic HeLa extracts 4.1R, we the assembly of mitotic asters by the of 4.1R from the extract. In to the assembly the extracts with of We used to the to 4.1R, its proteins NuMA and from the extracts. not 4.1R, tubulin from the cell because showed that proteins in protein and of the that 4.1R, and tubulin in the in and of 4.1R and of NuMA and tubulin in the The the of 4.1R and a of NuMA tubulin The not 4.1R, tubulin 4.1R from the of NuMA and tubulin in the The in vitro aster assembly using the from the We of assembly from and extracts on and for and NuMA to the of aster Three aster of the extracts with not the of the mitotic asters the of the NuMA protein at the of The asters assembled from the have and to the The assembly is to that of the in asters We asters of 4.1R from the extract with the the assembly of the mitotic asters and randomly microtubules asters in The of aster assembly in the extracts not to of NuMA because showed that the of NuMA and in the and extracts. results demonstrated that organization of microtubules into asters 4.1R a complex in a cell-free 4.1R is the component from the extract using the we the recombinant 4.1R protein mitotic aster formation in the extracts. We the of 4.1R to into the by the of of in a single mitotic we of recombinant and of mitotic HeLa extract with We used to the and the protein with the for the We that mitotic HeLa cell of The of recombinant at a of is to that of from mitotic HeLa The assays using extracts from mitotic HeLa cells that have been to immunodepletion with of the extract with recombinant at to to of mitotic aster formation The reconstituted assembly assembly and resulted in asters The of recombinant to the extract at and not to the of aster the of the asters and through a recombinant with NuMA and tubulin from the mitotic microtubule results suggest that a 135-kDa 4.1R isoform is for mitotic aster formation in a cell-free Protein 4.1R and in of 4.1R and tubulin at the spindle and spindle the interaction of 4.1R with microtubules in and the of 4.1R in mitotic aster assembly to the 4.1R associate with tubulin in We assays using mitotic extracts from highly synchronized HeLa cells with to with 4.1R S.C. Snyder M. Marchesi V.T. Benz Jr., E.J. J. Cell Biol. 1999; PubMed Scopus Google and tubulin L. A. J. Cell Sci. Google Scholar), and and using and and a 135-kDa 4.1R isoform not of and for the of 4.1R of a 135-kDa 4.1R isoform in both at and results suggest that a 135-kDa 4.1R isoform in vivo in a complex with NuMA and We further the association of 4.1R, and tubulin by the with of a using a tubulin from and a tubulin from both and the a NuMA from and a from both and In with S.C. Snyder M. Marchesi V.T. Benz Jr., E.J. J. Cell Biol. 1999; PubMed Scopus Google and that of and associates J.A. T. S. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar), results that NuMA and 4.1R NuMA and tubulin in a complex in results that 4.1R, and NuMA associate the mitotic of the cell cycle. The of tubulin by the of 4.1R that with tubulin by and the of the 4.1R isoform that with tubulin suggest that a 135-kDa 4.1R isoform from the translation initiation associates with tubulin in the interaction of isoforms of 4.1R with we used a to 4.1R to of the domain been shown to to 4.1R. not with family (8Walensky L.D. Blackshaw S. Liao D. Watkins C.C. Weier H.U. Parra M. Huganir R.L. Conboy J.G. Mohandas N. Snyder S.H. J. Neurosci. 1999; 19: 6457-6467Crossref PubMed Google Scholar, 9Ohara R. Yamakawa H. Nakayama M. Yuasa S. Ohara O. Brain Res. Dev. Brain Res. 1999; 117: 127-138Crossref PubMed Scopus (18) Google Scholar, 10Tran Y.K. Bogler O. Gorse K.M. Wieland I. Green M.R. Newahsm I.F. Cancer Res. 1999; 59: 35-43PubMed Google Scholar, 11Parra M. Gascard P. Walensky L.D. Gimm J.A. Blackshaw S. Chan N. Takakuwa Y. Berger T. Lee G. Chasis J.A. Snyder S.H. Mohandas N. Conboy J.G. J. Biol. Chem. 2000; 275: 3247-3255Abstract Full Text Full Text PDF PubMed Scopus (118) Google Scholar), we used an to 4.1R isoforms that interact with We and not from the showed a 135-kDa 4.1R and with S.C. Snyder M. Marchesi V.T. Benz Jr., E.J. J. Cell Biol. 1999; PubMed Scopus Google that a 135-kDa 4.1R isoform associates with NuMA in a mitotic complex, a 135-kDa 4.1R in NuMA of with the an of further suggest that a 135-kDa isoform of 4.1R with tubulin and NuMA in mitotic HeLa The results suggest that a of a 135-kDa 4.1R isoform in vivo in a complex with a of the mitotic proteins tubulin and of 4.1R and tubulin associate we the of and by both the protein and We used cell from mitotic cells with of and for from that of 4.1R by that of tubulin and that of tubulin by in of 4.1R. with S.C. Snyder M. Marchesi V.T. Benz Jr., E.J. J. Cell Biol. 1999; PubMed Scopus Google Scholar), 4.1R and NuMA with of NuMA by that 4.1R. The of with that a of associate in is with that of 4.1R and tubulin partially co-localize Protein 4.1R been to localize at the spindle and spindle poles of mitotic cells S. Gascard P. S. Mohandas N. Chasis J.A. J. Cell Biol. PubMed Scopus Google Scholar, Chasis J.A. Mohandas N. G. S. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar, S.C. Snyder M. Marchesi V.T. Benz Jr., E.J. J. Cell Biol. 1999; PubMed Scopus Google is the and of 4.1R to the of the mitotic the microtubules, its function in spindle/spindle In we that 4.1R with microtubules at the mitotic spindle and spindle with microtubules in with tubulin in and associates with tubulin in mitotic HeLa cell extracts through its and Furthermore, we that 4.1R is a mitotic microtubule-associated protein and is to mitotic aster assembly in vitro in a cell-free extract from synchronized HeLa on we that non-erythroid 4.1R to the organization of mitotic The cell of 4.1R is it to the and and to the spindle poles at 4.1R partially with two of the mitotic and microtubules. We S.C. Snyder M. Marchesi V.T. Benz Jr., E.J. J. Cell Biol. 1999; PubMed Scopus Google showed that 4.1R directly with NuMA through its C-terminal domain and a complex with the spindle proteins dynein, and cell We in to its interaction with 4.1R with tubulin in mitotic cells and is a mitotic microtubule-associated been that 4.1R from red blood cells with the C-terminal domain of tubulin I. J. J. 1988; Google Scholar). In 4.1R isoforms co-localize and interact with microtubules through a of the domain I. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). with showed a of 4.1R and tubulin in HeLa and in vitro sedimentation the interaction of an isoform with microtubules. Moreover, we showed that a HeLa isoform of the and with microtubules. Furthermore, we demonstrated that both and isoforms associate with tubulin in a pull-down using HeLa mitotic extracts. In to the interaction of 4.1R isoforms with tubulin I. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar), an interaction that the we that both the and the of 4.1R to its to tubulin in HeLa mitotic extracts. modifications of tubulin have been shown to its association with microtubule-associated proteins D. S. P. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). tubulin in cells of different and it associates with the the and the Y. M. E. M. Cell PubMed Scopus Google Scholar). The of 4.1R with that of tubulin it is that the post-translational of tubulin in mitotic cells of 4.1R isoforms through into microtubule a protein in the interaction of mitotic tubulin and the of 4.1R. protein is because NuMA with tubulin through L. A. J. Cell Sci. Google and with the of 4.1R through S.C. Snyder M. Marchesi V.T. Benz Jr., E.J. J. Cell Biol. 1999; PubMed Scopus Google Scholar). that the of NuMA 4.1R to proteins form a a we demonstrated that 4.1R appears to interact in vivo with NuMA with NuMA and tubulin the of 4.1R from the mitotic HeLa extracts not the interaction of NuMA and shown through association in randomly dispersed microtubules assembled in extracts to 4.1R associates with NuMA and tubulin the association of 4.1R, and tubulin that 4.1R a role in mitotic formation that depends on the of structural and microtubule proteins directly demonstrated spindle assembly in extracts from R. R. T. R. P. A. E. 1996; PubMed Scopus Google Scholar). and formation by the of microtubule asters in the of the in both F. E. J. Cell Biol. 1991; PubMed Scopus Google and mammalian T. J. Cell Biol. PubMed Scopus Google Scholar). in vitro aster assembly using HeLa mitotic an that of the structural in been used to the function of a of proteins at the spindle poles L. A. G. J. Cell Biol. 1999; PubMed Scopus Google Scholar, A. J. Biol. Chem. 2000; 275: Full Text Full Text PDF PubMed Scopus Google Scholar, J.A. T. S. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar, Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar, T. A. J. Cell Biol. PubMed Scopus Google Scholar). We used to that mitotic aster assembly in a 4.1R and that assembly with recombinant results suggest that 4.1R is to the assembly of mitotic asters in vitro. Our assays showed that a of NuMA and with 4.1R. with the immunodepletion assays further that 4.1R to of NuMA and results that aster assembly is not because of the of NuMA is further by the that NuMA associates with the microtubules in the assembly of 4.1R not to the association of NuMA with of 4.1R to the by tubulin NuMA for assembly of The of 4.1R in formation in cells is 4.1R the interaction dynein, and microtubules in a to its role in the of the association of actin, and proteins in red blood 4.1R have been D. Chasis J.A. Parra M. Lee G. M. Walensky L. Mohandas N. E. Conboy J.G. J. 1999; PubMed Scopus Google Scholar). The of is the of 4.1R and its in cell it is not that that of have because of J. A. PubMed Scopus Google Scholar, T. T. Full Text Full Text PDF PubMed Scopus Google Scholar). the of in cells that from of function J. T. 2003; PubMed Scopus Google Scholar). In cell division, the function of 4.1R in 4.1R by and family is that not in HeLa and in is highly in the for that a splicing in family of the isoforms to in is to the of family the of 4.1R to interact with mitotic tubulin and the that mitotic aster assembly in vitro 4.1R suggest that 4.1R to the structural organization and of the mitotic cell is by an in vitro aster assembly using extracts Lee G. Chasis J.A. Mohandas N. R. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google that that the and the microtubule array and dispersed the of Furthermore, of 4.1R in HeLa cells resulted in spindle poles in mitotic the role of 4.1R in the of the mitotic that 4.1R is and is to mitotic tubulin We and Chan for that to We for with the of of 4.1R in mitotic HeLa We Mohandas and Blood for a and the for the of 4.1R from
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