Plant kinesin-like calmodulin-binding protein (KCBP) is a novel member of the kinesin superfamily that interacts with calmodulin (CaM) via its CaM-binding domain (CBD). Activated CaM (Ca2+-CaM) has been shown to inhibit KCBP interaction with microtubules (MTs) thereby abolishing its motor- and MT-dependent ATPase activities. To test whether the fusion of CBD to non-CaM-binding kinesins confers Ca2+-CaM regulation, we fused the CBD of KCBP to the N or C terminus of a minus-end (non-claret disjunction) or C terminus of a plus-end (Drosophila kinesin) motor. Purified chimeric kinesins bound CaM in a Ca2+-dependent manner whereas non-claret disjunction, Drosophila kinesin, and KCBP that lack a CBD did not. As in the case of KCBP with CBD, the interaction of chimeric motors with MTs, as well as their MT-stimulated ATPase activity, was inhibited by Ca2+-CaM. The presence of a spacer between the motor and CBD did not alter Ca2+-CaM regulation. However, KCBP interaction with MTs and its MT-stimulated ATPase activity were not inhibited when the motor domain and CBD were added separately, suggesting that Ca2+-CaM regulation of CaM-binding motors occurs only when the CBD is attached to the motor domain. These results show that the fusion of the CBD to animal motors confers Ca2+-CaM regulation and suggest that the CBD functions as a modular domain in disrupting motor-MT interaction. Our data also support the hypothesis that CaM-binding kinesins may have evolved by addition of a CBD to a kinesin motor domain. Plant kinesin-like calmodulin-binding protein (KCBP) is a novel member of the kinesin superfamily that interacts with calmodulin (CaM) via its CaM-binding domain (CBD). Activated CaM (Ca2+-CaM) has been shown to inhibit KCBP interaction with microtubules (MTs) thereby abolishing its motor- and MT-dependent ATPase activities. To test whether the fusion of CBD to non-CaM-binding kinesins confers Ca2+-CaM regulation, we fused the CBD of KCBP to the N or C terminus of a minus-end (non-claret disjunction) or C terminus of a plus-end (Drosophila kinesin) motor. Purified chimeric kinesins bound CaM in a Ca2+-dependent manner whereas non-claret disjunction, Drosophila kinesin, and KCBP that lack a CBD did not. As in the case of KCBP with CBD, the interaction of chimeric motors with MTs, as well as their MT-stimulated ATPase activity, was inhibited by Ca2+-CaM. The presence of a spacer between the motor and CBD did not alter Ca2+-CaM regulation. However, KCBP interaction with MTs and its MT-stimulated ATPase activity were not inhibited when the motor domain and CBD were added separately, suggesting that Ca2+-CaM regulation of CaM-binding motors occurs only when the CBD is attached to the motor domain. These results show that the fusion of the CBD to animal motors confers Ca2+-CaM regulation and suggest that the CBD functions as a modular domain in disrupting motor-MT interaction. Our data also support the hypothesis that CaM-binding kinesins may have evolved by addition of a CBD to a kinesin motor domain. Kinesins, a superfamily of microtubule (MT) 1The abbreviations used are: MT, microtubule; KCBP, kinesin-like calmodulin-binding protein; CaM, calmodulin; CBD, CaM-binding domain; NCD, non-claret disjunction; DK, Drosophila kinesin; AMP-PNP, adenosine 5′-(β,γ-imino)triphosphate; HRP-CaM, horseradish peroxidase-conjugated CaM; Ca2+-CaM, activated CaM; MHC, myosin heavy-chain; aa, amino acids; S, spacer; Pipes, 1,4-piperazinediethanesulfonic acid; 1.5C, C terminus of KCBP with motor and CBD; 1.0C, C terminus of KCBP with motor domain only; 0.4C, C terminus of KCBP with CBD only; At, Arabidopsis thaliana. motors, are involved in a variety of cellular processes including transport of vesicle, organelle and RNA·protein complexes, morphogenesis, spindle formation, chromosome movement, nuclear fusion, and signal transduction (1Goldstein L.S.B. Philip A.V. Annu. Rev. Cell Dev. Biol. 1999; 15: 141-183Google Scholar, 2Reddy A.S.N. Intl. Rev. Cytol. Cell Biol. 2001; 204: 98-179Google Scholar). Structurally kinesins contain a highly conserved motor domain that binds MTs and hydrolyzes ATP, a neck (determines motor directionality on MTs), a coiled-coil region (aids in dimerization), and a variable tail domain (involved in regulation of motor activity and/or in cargo carrying) (3Vale R.D. Fletterick R.J. Annu. Rev. Cell Dev. Biol. 1997; 13: 745-777Google Scholar, 4Schliwa M. Woehlke G. Nature. 2001; 411: 424-425Google Scholar). The motor domain can be at the N or C terminus or in the middle. The N-terminal motors move toward the fast growing plus-end of MTs whereas the C-terminal motors translocate to the slow growing minus-end of MTs (3Vale R.D. Fletterick R.J. Annu. Rev. Cell Dev. Biol. 1997; 13: 745-777Google Scholar, 5Endow S.A. Nat. Cell. Biol. 1999; 1: E163-E167Google Scholar, 6Vale R.D. Milligan R.A. Science. 2000; 288: 88-95Google Scholar). Recent genome sequence projects, coupled with cell and molecular biological studies in animals and plants, revealed that although both plants and animals contain some common motors plants are unique in containing a large number of kinesins (61 in Arabidopsis) including several plant-specific ones (7Reddy A.S.N. Day I.S. BioMed Central Genomics. 2001; 2: 2Google Scholar). Studies with a few plant kinesins indicate that they are regulated by novel mechanisms and perform plant-specific functions (2Reddy A.S.N. Intl. Rev. Cytol. Cell Biol. 2001; 204: 98-179Google Scholar, 8Reddy A.S.N. Schliwa M. Molecular Motors. Verlag GMBH, Wiley VCH, Germany2002Google Scholar, 9Nishihama R. Soyano T. Ishikawa M. Araki S. Tanaka H. Asada T. Irie K. Ito M. Terada M. Banno H. Yamazaki Y. Machida Y. Cell. 2002; 109: 87-99Google Scholar). One of the plant kinesins, kinesin-like calmodulin-binding protein (KCBP), a minus-end motor, was isolated from a number of dicot and monocot plants as a calmodulin (CaM)-interacting protein (10Reddy A.S.N. Safadi F. Narasimhulu S.B. Golovkin M. Hu X. J. Biol. Chem. 1996; 271: 7052-7060Google Scholar, 11Abdel-Ghany S.E. Reddy A.S.N. DNA Cell Biol. 2000; 19: 567-578Google Scholar, 12Reddy A.S.N. Narasimhulu S.B. Safadi F. Golovkin M. Plant J. 1996; 10: 9-21Google Scholar, 13Wang W. Takezawa D. Narasimhulu S.B. Reddy A.S.N. Poovaiah B.W. Plant Mol. Biol. 1996; 31: 87-100Google Scholar). The CaM-binding domain (CBD) in KCBP is mapped to the C terminus of the motor domain (10Reddy A.S.N. Safadi F. Narasimhulu S.B. Golovkin M. Hu X. J. Biol. Chem. 1996; 271: 7052-7060Google Scholar). Although a CaM-binding kinesin has not been identified in the completely sequenced genomes of Saccharomyces cerevisiae,Schizosaccharomyces pombe, Caenorhabditis elegans, Drosophila melanogaster, and Homo sapiens (7Reddy A.S.N. Day I.S. BioMed Central Genomics. 2001; 2: 2Google Scholar, 14Miki H. Setou M. Kaneshiro K. Hirokawa N. Proc. Natl. Acad. Sci. U. S. A. 2001; 98: 7004-7011Google Scholar), a kinesin (kinesin-C) that binds to CaM has been isolated from sea urchin (15Rogers G.C. Hart C.L. Wedman K.P. Scholey J.M. J. Mol. Biol. 1999; 294: 1-8Google Scholar). KCBP and kinesin-C are similar in a conserved motor domain at the C and a CBD kinesins with CaM in a Ca2+-dependent However, the KCBP and kinesin-C in the the of coiled-coil region and the tail domain KCBP a and a domain in tail of some animal and whereas kinesin-C (7Reddy A.S.N. Day I.S. BioMed Central Genomics. 2001; 2: 2Google Scholar, Reddy A.S.N. 1999; 15: Scholar). KCBP is involved in plant-specific processes as and is with the and in are in animal J. K. D. Proc. Natl. Acad. Sci. U. S. A. 1997; Scholar, A.S.N. Day I.S. Plant Sci. 2000; Scholar, J. Reddy Plant J. 1997; Scholar, U. U. S. S. Day Reddy A.S.N. G. M. J. 2002; Scholar). in has been shown that KCBP several of cell Safadi F. Reddy Plant Cell. 2000; Scholar). Although the of kinesin-C is not is in Ca2+-dependent by in (15Rogers G.C. Hart C.L. Wedman K.P. Scholey J.M. J. Mol. Biol. 1999; 294: 1-8Google Scholar). The mechanisms that the activity of kinesins, with a few are Intl. Rev. Cytol. Cell Biol. 2001; 204: Scholar). motor have been used to directionality motor and functions of of kinesin from a number of S.A. Nat. Cell. Biol. 1999; 1: E163-E167Google Scholar, S.A. Science. Scholar, M. Y. Hirokawa N. Cell. 2000; Scholar, U. Schliwa M. Nature. 1997; Scholar, N. Hart C.L. R.D. Cell. 1997; Scholar, J. S. S. Schliwa M. J. 1999; Scholar, K. U. Schliwa M. T. R.A. J. 2000; 19: Scholar). that motor directionality have been by neck between and minus-end motors S.A. Science. Scholar, U. Schliwa M. Nature. 1997; Scholar, N. Hart C.L. R.D. Cell. 1997; Scholar). These chimeric motors of their motor and kinesin move and minus-end of neck of chimeric motors revealed the directionality S.A. Nat. Cell. Biol. 1999; 1: E163-E167Google Scholar, S.A. Science. Scholar, Hart C.L. A. R.D. Fletterick R.J. Nature. Scholar). However, the chimeric has been that the myosin motor not the directionality in K. M. J. R. M. Nature. 2001; Scholar). of chimeric have also been to and regulation of of the myosin M. K. M. Proc. Natl. Acad. Sci. U. S. A. 1997; Scholar, Nature. Scholar, M. K. Y. K. A. M. J. Biol. Chem. 2001; Scholar). a chimeric myosin of motor domain and and has been shown that the ATPase activity of chimeric MHC, not the MHC, is regulated by M. K. M. Proc. Natl. Acad. Sci. U. S. A. 1997; Scholar). the case of KCBP, activated CaM (Ca2+-CaM) the motor activity and its interaction with MTs H. Golovkin M. Reddy A.S.N. S.A. Proc. Natl. Acad. Sci. U. S. A. 1997; Scholar, S.B. Reddy A.S.N. Plant Cell. 10: Scholar, Reddy A.S.N. R.A. Cell Scholar). Although kinesin-C a CBD, the of the domain in motor activity is not (15Rogers G.C. Hart C.L. Wedman K.P. Scholey J.M. J. Mol. Biol. 1999; 294: 1-8Google Scholar). and the in kinesins are highly conserved in (2Reddy A.S.N. Intl. Rev. Cytol. Cell Biol. 2001; 204: 98-179Google Scholar, 6Vale R.D. Milligan R.A. Science. 2000; 288: 88-95Google Scholar). To test whether the CBD of KCBP functions as a in non-CaM-binding kinesins, we fused the CBD of KCBP to the N or C terminus of a minus-end and to the C terminus of a plus-end (Drosophila kinesin, motor with between the motor and have the their and MT-stimulated ATPase in the presence of and/or CaM CaM show that the and MT-stimulated ATPase of both and C-terminal chimeric motors are inhibited by CaM or Arabidopsis CaM in a Ca2+-dependent suggesting that the CBD of plant KCBP as a in animal chimeric spacer between the motor and CBD not alter Ca2+-CaM regulation of chimeric the CBD confers Ca2+-CaM regulation in not in and were from and to were from CaM was from The was from Molecular and were from was from were of The region the CBD of Arabidopsis KCBP was (10Reddy A.S.N. Safadi F. Narasimhulu S.B. Golovkin M. Hu X. J. Biol. Chem. 1996; 271: 7052-7060Google Scholar). The sequence in was the and with The was with and containing the CBD of KCBP to The sequence in was the and with The was with and containing the CBD of KCBP to The sequence the CBD was by the CBD from with The sequence the CBD was by the with and the was of 1.5C, 1.0C, and KCBP was (10Reddy A.S.N. Safadi F. Narasimhulu S.B. Golovkin M. Hu X. J. Biol. Chem. 1996; 271: 7052-7060Google Scholar, S.B. Reddy A.S.N. Plant Cell. 10: Scholar). The molecular of the and KCBP with CBD, NCD, and DK, and KCBP CBD are and The with a spacer and CBD was by sequence to and with the has a spacer of neck and coiled-coil between the motor domain and The molecular of the is with the CBD at the N terminus of was by the CBD sequence from KCBP and with amino to of in in The molecular of the protein is The and were by The of the fusion in was by to a of at the were and with The were by the in and on and at The motor containing the CBD were a was used to the motor the The containing the motor with a CBD was a and with the and with and The containing the motor a CBD was a with and with and with containing were and at and were on with or and with horseradish CaM, or with F. Reddy Reddy A.S.N. J. Biol. Chem. 2000; Scholar). The and of and Arabidopsis CaM was as F. Reddy Reddy A.S.N. J. Biol. Chem. 2000; Scholar). The of motor and CaM was by the and on Safadi F. Reddy A.S.N. J. Biol. Chem. 1999; Scholar). of and was in a and at S.B. Reddy A.S.N. Plant Cell. 10: Scholar). The MTs were by to a of at the MTs were at at and the was in Pipes, The was in a containing motor protein or KCBP protein with or MTs S.B. Reddy A.S.N. Plant Cell. 10: Scholar). CaM CaM AMP-PNP, or were also at the were in a at at The and were with and by The and motor were by the with KCBP and motor with were and was and the was and with or HRP-CaM, as The of the motor was at The ATPase activity of the motors was in a and containing motor protein with or MTs and W. Mol. Biol. 2001; Scholar). and to a of and were also added in at of and of were added to the and at W. Mol. Biol. 2001; Scholar). The was of The ATPase activity of the motor was in of of motor protein were in was at from were To whether the CBD of a plant motor functions as a modular we fused the CBD of a plant KCBP to the C terminus of Drosophila kinesins, and DK, a C-terminal motor, and N-terminal motor, The motor with a CBD 1.5C, and were a and motor a CBD 1.0C, NCD, and with a were a The and motor are shown in the motor a were and with HRP-CaM, or As and KCBP with CaM whereas NCD, DK, and KCBP that lack a CBD did not with CaM in chimeric motors did not CaM in the presence of a not These results suggest that the chimeric motors and bound CaM in a Ca2+-dependent and the plant kinesin CBD confers CaM to animal NCD, and KCBP that contain were by whereas KCBP and with were by KCBP from plants (10Reddy A.S.N. Safadi F. Narasimhulu S.B. Golovkin M. Hu X. J. Biol. Chem. 1996; 271: 7052-7060Google and kinesin-C from sea urchin (15Rogers G.C. Hart C.L. Wedman K.P. Scholey J.M. J. Mol. Biol. 1999; 294: 1-8Google are the only CaM-binding we have shown that the activity of KCBP is by CaM H. Golovkin M. Reddy A.S.N. S.A. Proc. Natl. Acad. Sci. U. S. A. 1997; Scholar, S.B. Reddy A.S.N. Plant Cell. 10: Scholar, Reddy A.S.N. R.A. Cell Scholar). we whether the fusion of plant kinesin CBD to animal and minus-end motors confers Ca2+-CaM regulation. The has a spacer whereas in the the CBD is from the motor by the neck and a coiled-coil region of amino we the of motor 1.5C, and to MTs a in the presence of ATP, CaM, or Ca2+-CaM. As shown in the KCBP motor protein with MTs in the in the presence of and or the presence of Ca2+-CaM or Arabidopsis and AMP-PNP, the motor protein did not with the MTs and in the suggesting that motor protein interaction with MTs is inhibited by Ca2+-CaM the KCBP motor with the a was and with KCBP the CBD and with the MTs in the presence of and CaM, or both KCBP motor, KCBP 1.5C, in the in the presence of These results suggest that plant CaM CaM, the interaction of KCBP motor its CaM-binding domain. the we the interaction of chimeric and motor with As shown in although or in the of MTs in the when with MTs they with MTs in the presence of and or CaM However, when was with MTs in the presence of and both and CaM or in the presence of the motor protein did not and with the MTs and CBD and with the MTs the presence of Ca2+-CaM. These results show that and are regulated in the manner as KCBP and KCBP by Ca2+-CaM, the of Ca2+-CaM on the chimeric in the CBD is fused to a plus-end motor and motor domain in the with MTs, a was and with to the motor protein KCBP and the is also regulated by Ca2+-CaM the presence of both Ca2+-CaM, not in the presence of or CaM chimeric motor did not MTs, and the motor protein in the CBD; to bound with MTs in the presence of both Ca2+-CaM Our results with the CBD in are in with the activity of the motor H. S.A. 1996; Scholar). we fused plant CBD to animal motors and used CaM to show the regulation of chimeric and motors with MTs, we whether Arabidopsis and the chimeric motors in a Ca2+-dependent Although in a few amino Safadi F. Reddy A.S.N. J. Biol. Chem. 1999; Scholar), they inhibited the interaction of chimeric motors and with MTs and on the interaction of motors CBD and and the presence of and of the or the motors with CBD in the and whereas the motors CBD with MTs and These results indicate that and CaM are to with motors and inhibit their interaction with These data suggest that activated CaM the chimeric and motors, as well as KCBP in a similar although and are and motors that perform functions in is involved in transport and is whereas is involved in spindle and chromosome in and in and (1Goldstein L.S.B. Philip A.V. Annu. Rev. Cell Dev. Biol. 1999; 15: 141-183Google Scholar, Intl. Rev. Cytol. Cell Biol. 2001; 204: Scholar). To the Ca2+-CaM regulation of chimeric motors, we MT-stimulated ATPase activity of motors in the presence of CaM, or CaM of motor interaction with MTs, and has KCBP Safadi F. Reddy A.S.N. J. Biol. Chem. 1999; Scholar), we used in ATPase KCBP, NCD, and with or CBD ATPase activity in the of MTs The ATPase activity of KCBP, NCD, and with and CBD in the presence of MTs is by The MT-stimulated ATPase activity of motors with or the CBD was not in the presence of or suggesting that is of the fusion of the CBD to and motors on the ATPase of the as in the the MT-stimulated ATPase activity of KCBP 1.5C, and was by and in the presence of both and However, the MT-stimulated ATPase activity of motors the CBD was not inhibited in the presence of and MT-stimulated ATPase activity of KCBP 1.5C, and was to in the presence of These results show that the MT-stimulated ATPase activity of KCBP and chimeric and motors is inhibited by Ca2+-CaM the The in MT-dependent ATPase activity of KCBP and kinesin may be of the presence of of coiled-coil region in the and/or MT-stimulated ATPase activity with has been shown to be in the of to R. A. S.A. J. Biol. Chem. Scholar, R.A. 1999; Scholar). The MT-dependent ATPase activity of and of is also M. J. Nat. Cell. Biol. 1999; 1: Scholar). Studies with and that have a spacer amino have that can be at a from the motor. To test whether a spacer between the motor and the CBD Ca2+-CaM regulation we we the coiled-coil region of to between the motor and the CBD The protein bound and was a in a Ca2+-dependent manner suggesting that the spacer between the motor and the CBD not chimeric motor interaction with To test the regulation of motor protein by Ca2+-CaM, the chimeric motor was used in and ATPase As shown in the protein with the MTs in the presence of and or in the presence of and in the the ATPase activity of the chimeric motor was inhibited by The of Ca2+-CaM on MT-stimulated ATPase activity was by the addition of These results suggest that a spacer amino between the motor and the CBD not Ca2+-CaM regulation of chimeric motor. the that we used have the CBD at the C terminus of the motor domain. To test whether the CBD fusion to the N terminus of the motor confers Ca2+-CaM regulation, we a we fused the CBD to the N terminus of the motor and the CBD is from the motor by a spacer of amino coiled-coil and neck of The chimeric protein bound and in a Ca2+-dependent manner suggesting that the of the CBD and the spacer between the CBD and motor not the interaction of motor with To the regulation of chimeric motor by Ca2+-CaM, the motor protein was used in and ATPase Ca2+-CaM also regulated motor functions of The protein with the MTs in the presence of and or However, in the presence of and in the The MT-stimulated ATPase activity of the was also inhibited in the presence of Ca2+-CaM by The of Ca2+-CaM on ATPase activity was in the presence of These data suggest that between the CBD and the motor the of the CBD in the protein or C terminus to the Ca2+-CaM regulation of the chimeric motor. To test whether the CBD as a modular domain we used (CBD) and KCBP in and ATPase As shown in the CBD protein in the in the in the presence of and of the presence of or or These results suggest that the CBD protein not with CBD and KCBP in and ATPase the the motor and CBD of KCBP in the in the of MTs However, when with MTs in the presence of AMP-PNP, the with MTs, CBD in the suggesting that and motor not a interaction of KCBP protein with MTs was not in the presence of the CBD or of These data indicate that the CBD not Ca2+-CaM regulation as in with CBD; The ATPase activity of KCBP motor protein was also not inhibited in the presence of CBD protein in or These results that the CBD of KCBP as a modular domain only in not in we used and N-terminal motors, the sequence and are highly conserved between R.D. Milligan R.A. Science. 2000; 288: 88-95Google Scholar, Hart C.L. A. R.D. Fletterick R.J. Nature. Scholar, R. R.D. Fletterick R.J. Nature. 1996; Scholar). added the CBD to the C terminus of with a spacer and with a or C terminus with a or N terminus with a coiled-coil and neck of chimeric kinesins with a CBD bound CaM in a Ca2+-dependent and chimeric with a CBD, not a CBD, bound and CaM not in the presence of chimeric bound in a Ca2+-dependent manner and regulation of was and ATPase Ca2+-CaM inhibited of chimeric animal motors containing a CBD with MTs and their MT-stimulated ATPase activity to However, activated CaM did not the of animal motors the CBD to suggesting that the of Ca2+-CaM on motor functions is by the regulation of chimeric motors was not by the CBD from the motor domain with a spacer of to amino acids; to that the CBD is at a from the motor domain in motor-MT interaction. used of coiled-coil spacer and or spacer and both similar results to Ca2+-CaM regulation of chimeric motors was not by the of the The presence of a CBD at the C or N terminus to the motor with or spacer similar regulation the interaction of motor with MTs was to However, Ca2+-CaM regulation was motor domain and CBD were added to the or ATPase that the CBD functions only not in The of the motors revealed that and KCBP in C-terminal and in N-terminal kinesin (7Reddy A.S.N. Day I.S. BioMed Central Genomics. 2001; 2: 2Google with and functions (1Goldstein L.S.B. Philip A.V. Annu. Rev. Cell Dev. Biol. 1999; 15: 141-183Google Scholar, Intl. Rev. Cytol. Cell Biol. 2001; 204: Scholar). chimeric motors are regulated in a similar However, the of and R. R.D. Fletterick R.J. Nature. 1996; Scholar, R. Fletterick R.J. R.D. Nature. 1996; Scholar, Plant Biol. 2000; have shown that N and C of motors are and on the from the the CBD in is to be on the of the on we the CBD in CaM-binding kinesins functions as a in Ca2+-CaM regulation to both and plus-end motors of CaM and Arabidopsis CaM were in chimeric Arabidopsis has conserved CaM and (2Reddy A.S.N. Intl. Rev. Cytol. Cell Biol. 2001; 204: 98-179Google Scholar, I.S. Reddy Reddy A.S.N. Biol. 2002; Scholar). in and and and amino from and whereas from in amino and CaM from Arabidopsis and in and amino at the amino plant and animal are in chimeric motor and MT-stimulated ATPase activities. the presence of Ca2+-CaM, the kinesins show activity and MT-stimulated ATPase activity interaction with MTs, and their MT-stimulated ATPase activity has been the of to the mechanisms of regulation of the and To the that in the motor domain kinesin interaction with MTs and several and molecular as and of and kinesins have been used R.D. Milligan R.A. Science. 2000; 288: 88-95Google Scholar, M. Y. Hirokawa N. Cell. 2000; Scholar, R. R.D. Fletterick R.J. Nature. 1996; Scholar, R. Fletterick R.J. R.D. Nature. 1996; Scholar, H. A. M. Fletterick R.J. R.D. Milligan R.A. Cell. 1997; Scholar, M. Y. H. Fletterick R.J. Hirokawa N. Nature. 2001; 411: Scholar, G. Hart C.L. N. R.D. Cell. 1997; Scholar, J. J. R.A. J. Scholar). These studies revealed that and and to are highly conserved in in have their in motor in highly conserved amino in and have been shown to alter motor functions H. S.A. Nature. Scholar, M. X. S.A. J. 2001; Scholar, H. S. J. 1996; 15: Scholar, J. Biol. Chem. 2000; Scholar). The and in and ATPase MT-stimulated ATPase activity H. S.A. Nature. Scholar, M. X. S.A. J. 2001; Scholar, H. S. J. 1996; 15: Scholar). they are in the signal from and to in the M. X. S.A. J. 2001; Scholar). that between and M. X. S.A. J. 2001; Scholar), Ca2+-CaM may the of in kinesins in of interaction between motors and These Ca2+-CaM in the motor the between and of Ca2+-CaM to kinesin motor interaction with The CBD containing kinesins be in in the at in and coupled with studies of motors in the presence or of Ca2+-CaM and MTs, are to the mechanisms by Ca2+-CaM CaM-binding kinesins Our results to with studies suggest that the of Ca2+-CaM is of the of in the motor. of motor-MT interaction by activated CaM be activated CaM binds the CBD the may the on the motor thereby the interaction of motor with the MTs, or the of CaM to CBD results in in the motor and in and thereby the interaction between the C-terminal region of the and the of the motor. These mechanisms are not The that the CBD not Ca2+-CaM regulation in that the not the motor domain. is also that the of the to the motor domain may be can in when is to the motor domain. The the of a of of motor that is to and the motor the is suggest that the CBD has to the of its to the N or C or fused to the CBD to a similar the in may on the motor domain. The in of the be of of or of or both the CBD region of the motor. the CBD region and of the motor contain that with of their Ca2+-CaM and MTs (10Reddy A.S.N. Safadi F. Narasimhulu S.B. Golovkin M. Hu X. J. Biol. Chem. 1996; 271: 7052-7060Google Scholar, G. Hart C.L. N. R.D. Cell. 1997; Scholar). and MT-dependent ATPase with KCBP with in the presence of that is similar to Ca2+-CaM not suggesting Ca2+-CaM may alter the interaction between the motor and of between the CBD and Ca2+-CaM between motor and Reddy A.S.N. R.A. Cell Safadi F. Reddy A.S.N. J. Biol. Chem. 1999; Scholar), the not only chimeric motor interaction with MTs to also KCBP motor from the Reddy A.S.N. R.A. Cell Scholar). However, in the of Ca2+-CaM, is of the CBD region on the interaction of the motor with MTs, as motors with or a CBD show similar and MT-stimulated ATPase to the CBD region not MTs the CBD in the presence of activated CaM may the interaction between motor and by or both we have that the CBD functions as a in Ca2+-CaM regulation to motors, and regulation is not on or of the CBD with to the motor domain. the CBD functions only in Our studies also suggest that CaM-binding kinesins in plants (KCBP) and animals (kinesin-C) may have evolved from kinesins by fusion of a of CaM A. and and and S. Day and on the
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