PRMT7 Is a Member of the Protein Arginine Methyltransferase Family with a Distinct Substrate Specificity

We have identified a mammalian arginine N-methyltransferase, PRMT7, that can catalyze the formation of ω-NG-monomethylarginine in peptides. This protein is encoded by a gene on human chromosome 16q22.1 (human locus AK001502). We expressed a full-length human cDNA construct in Escherichia coli as a glutathione S-transferase (GST) fusion protein. We found that GST-tagged PRMT7 catalyzes the S-adenosyl-methyl-3H-l-methionine-dependent methylation of the synthetic peptide GGPGGRGGPGG-NH2 (R1). The radiolabeled peptide was purified by high-pressure liquid chromatography and acid hydrolyzed to free amino acids. When the hydrolyzed products were separated by high-resolution cation-exchange chromatography, we were able to detect one tritiated species which co-migrated with an ω-NG-monomethylarginine standard. Surprisingly, GST-PRMT7 was not able to catalyze the in vitro methylation of a GST-fibrillarin (amino acids 1–148) fusion protein (GST-GAR), a methyl-accepting substrate for the previously characterized PRMT1, PRMT3, PRMT4, PRMT5, and PRMT6 enzymes. Nor was it able to methylate myelin basic protein or histone H2A, in vitro substrates of PRMT5. This specificity distinguishes PRMT7 from all of the other known arginine methyltransferases. An additional unique feature of PRMT7 is that it seems to have arisen from a gene duplication event and contains two putative AdoMet-binding motifs. To see if both motifs were necessary for activity, each putative domain was expressed as a GST-fusion and tested for activity with peptides R1 and R2 (acetyl-GGRGG-NH2). These truncated proteins were enzymatically inactive, suggesting that both domains are required for functionality. We have identified a mammalian arginine N-methyltransferase, PRMT7, that can catalyze the formation of ω-NG-monomethylarginine in peptides. This protein is encoded by a gene on human chromosome 16q22.1 (human locus AK001502). We expressed a full-length human cDNA construct in Escherichia coli as a glutathione S-transferase (GST) fusion protein. We found that GST-tagged PRMT7 catalyzes the S-adenosyl-methyl-3H-l-methionine-dependent methylation of the synthetic peptide GGPGGRGGPGG-NH2 (R1). The radiolabeled peptide was purified by high-pressure liquid chromatography and acid hydrolyzed to free amino acids. When the hydrolyzed products were separated by high-resolution cation-exchange chromatography, we were able to detect one tritiated species which co-migrated with an ω-NG-monomethylarginine standard. Surprisingly, GST-PRMT7 was not able to catalyze the in vitro methylation of a GST-fibrillarin (amino acids 1–148) fusion protein (GST-GAR), a methyl-accepting substrate for the previously characterized PRMT1, PRMT3, PRMT4, PRMT5, and PRMT6 enzymes. Nor was it able to methylate myelin basic protein or histone H2A, in vitro substrates of PRMT5. This specificity distinguishes PRMT7 from all of the other known arginine methyltransferases. An additional unique feature of PRMT7 is that it seems to have arisen from a gene duplication event and contains two putative AdoMet-binding motifs. To see if both motifs were necessary for activity, each putative domain was expressed as a GST-fusion and tested for activity with peptides R1 and R2 (acetyl-GGRGG-NH2). These truncated proteins were enzymatically inactive, suggesting that both domains are required for functionality. Protein arginine methylation is an apparently irreversible modification in which the guanidinium group of arginyl residues becomes methylated in a reaction with S-adenosylmethionine (AdoMet). 1The abbreviations used are: AdoMet, S-adenosyl-l-methionine; MBP, myelin basic protein; ADMA, asymmetric ω-NG,NG-dimethylarginine; SDMA, symmetric ω-NG,NG′-dimethylarginine; MMA, ω-NG-monomethylarginine; 3HAdoMet, S-adenosyl-methyl-3H-l-methionine; AdoHcy, S-adenosyl-l-homocysteine; HPLC, high-pressure liquid chromatography; MTA, 5′-deoxy-5′-methyl-thioadenosine; PRMT, protein arginine methyltransferase; THW loop, threonine-histidine/tryptophan loop.1The abbreviations used are: AdoMet, S-adenosyl-l-methionine; MBP, myelin basic protein; ADMA, asymmetric ω-NG,NG-dimethylarginine; SDMA, symmetric ω-NG,NG′-dimethylarginine; MMA, ω-NG-monomethylarginine; 3HAdoMet, S-adenosyl-methyl-3H-l-methionine; AdoHcy, S-adenosyl-l-homocysteine; HPLC, high-pressure liquid chromatography; MTA, 5′-deoxy-5′-methyl-thioadenosine; PRMT, protein arginine methyltransferase; THW loop, threonine-histidine/tryptophan loop. This modification has been implicated in the regulation of signal transduction (1Altschuler L. Wook J.O. Gurari D. Chebath J. Revel M. J. Int. Cyt. Res. 1999; 2: 189-195Crossref Scopus (40) Google Scholar, 2Bedford M.T. Frankel A. Yaffe M.B. Clarke S. Leder P. Richard S. J. Biol. Chem. 2000; 275: 16030-16036Abstract Full Text Full Text PDF PubMed Scopus (203) Google Scholar, 3Tang J. Kao P.N. Herschman H.R. J. Biol. Chem. 2000; 275: 19866-19876Abstract Full Text Full Text PDF PubMed Scopus (162) Google Scholar, 4Zhu W. Mustelin T. David M. J. Biol. Chem. 2002; 277: 35787-35790Abstract Full Text Full Text PDF PubMed Scopus (75) Google Scholar), transcription (5Chen D. Ma H. Hong H. Koh S.S. Huang S. Schurter B.T. Aswad D.W. Stallcup M.R. Science. 1999; 284: 2174-2177Crossref PubMed Scopus (983) Google Scholar, 6Fabbrizio I.E. El Messaoudi S. Polanowska J. Paul C. Cook J.R. Lee J.-H. Negre V. Rousset M. Pestka S. Le Cam A. Sardet C. EMBO Rep. 2002; 3: 641-645Crossref PubMed Scopus (175) Google Scholar, 7Yadev N. Lee J. Kim J. Shen J. Hu M.C.-T. Aldaz M. Bedford M.T. Proc. Natl. Acad. Sci. U. S. A. 2003; 100: 6464-6468Crossref PubMed Scopus (230) Google Scholar), RNA transport (8McBride A.E. Weiss V.H. Kim H.K. Hogle J.M. Silver P.A. J. Biol. Chem. 2000; 275: 3128-3136Abstract Full Text Full Text PDF PubMed Scopus (80) Google Scholar), and RNA splicing (9Friesen W.J. Paushkin S. Wyce A. Massenet S. Pesiridis G.S. Van Duyne G. Rappsilber J. Mann M. Dreyfuss G. Mol. Cell. Biol. 2001; 21: 8289-8300Crossref PubMed Scopus (310) Google Scholar). Four different types of protein arginine methyltransferases have been described. Type I enzymes catalyze the formation of ω-NG-monomethylarginine and ω-NG,NG-asymmetric dimethylarginine residues. Type II enzymes form ω-NG-monomethylarginine and ω-NG,NG′-symmetric dimethylarginine residues. Type III enzymes catalyze only the formation of ω-NG-monomethylarginine residues. Finally, type IV enzymes form δ-NG-monomethylarginine (for a review, see Ref. 10Gary J.D. Clarke S. Prog. Nucleic Acids Res. Mol. Biol. 1998; 61: 65-130Crossref PubMed Google Scholar). The previously described mammalian enzymes PRMT1, PRMT3, PRMT4/CARM1, and PRMT6 and the yeast enzyme RMT1 have been shown to be responsible for type I methylation (5Chen D. Ma H. Hong H. Koh S.S. Huang S. Schurter B.T. Aswad D.W. Stallcup M.R. Science. 1999; 284: 2174-2177Crossref PubMed Scopus (983) Google Scholar, 11Lin W.J. Gary J.D. Yang M.C. Clarke S. Herschman H.R. J. Biol. Chem. 1996; 271: 15034-15044Abstract Full Text Full Text PDF PubMed Scopus (386) Google Scholar, 12Tang J. Gary J.D. Clarke S. Herschman H.R. J. Biol. Chem. 1998; 273: 16935-16945Abstract Full Text Full Text PDF PubMed Scopus (270) Google Scholar, 13Gary J.D. Lin W.J. Yang M.C. Herschman H.R. Clarke S. J. Biol. Chem. 1996; 271: 12585-12594Abstract Full Text Full Text PDF PubMed Scopus (179) Google Scholar, 14Frankel A. Yadav N. Lee J. Branscombe T.L. Clarke S. Bedford M.T. J. Biol. Chem. 2002; 277: 3537-3543Abstract Full Text Full Text PDF PubMed Scopus (278) Google Scholar). The mammalian enzyme PRMT5/JBP1 catalyzes type II methylation (15Branscombe T.L. Frankel A. Lee J.H. Cook J.R. Yang Z. Pestka S. Clarke S. J. Biol. Chem. 2001; 276: 32971-32976Abstract Full Text Full Text PDF PubMed Scopus (292) Google Scholar), whereas the yeast RMT2 enzyme catalyzes type IV methylation (16Niewmierzycka A. Clarke S. J. Biol. Chem. 1999; 274: 814-824Abstract Full Text Full Text PDF PubMed Scopus (190) Google Scholar). No activity has currently been defined for the mammalian PRMT2 gene product, although its amino acid sequence is similar to that of the other PRMT gene products (17Qi C. Chang J. Zhu Y. Yeldandi A.V. Rao S.M. Zhu Y.J. J. Biol. Chem. 2002; 277: 28624-28630Abstract Full Text Full Text PDF PubMed Scopus (139) Google Scholar). In searching the human genome for novel protein arginine methyltransferases, we found a gene that appears to code for the seventh PRMT. A recombinantly expressed form of this PRMT is incapable of methylating GST-GAR, MBP, and histone H2A, typical substrates of the previously described protein arginine methyltransferases. However, this methyltransferase, now designated PRMT7, is able to methylate two arginine-containing peptides and exhibited type III enzymatic activity, catalyzing the formation of ω-NG-monomethylarginine residues. A similar species has recently been described in Chinese hamster cells, but the biochemical reaction catalyzed by it has not yet been determined (18Gros L. Delaporte C. Frey S. Decesse J. de Saint-Vincent B.R. Cavarec L. Dubart A. Gudkov A.V. Jacquemin-Sablon A. Cancer Res. 2003; 63: 164-171PubMed Google Scholar). Construction of PRMT7, PRMT7ΔC, and PRMT7ΔN Expression Vectors—The plasmid pGEX-PRMT7 was constructed by PCR amplification of a 2.1-kb fragment from a template of an IMAGE human cDNA clone (clone ID 2900965; GenBank accession number AW675040) with primers PRMT7-N1 (5′-CTA GTG TCG ACC ATG AAG ATC TTC TGC AGT CGG GCC-3′) and PRMT7-C1 (5′-CT CGC GGC CGC TCA GTC TTG GGT ATC TGC ATG CCT GAA CTC-3′). The PCR fragment was digested with SalI and NotI and ligated into pGEX(SN) (19Han L. Colicelli J. Mol. Cell. Biol. 1995; 15: 1318-1323Crossref PubMed Google Scholar). The plasmid pGEX-PRMT7ΔC was constructed by PCR-amplifying from pGEX-PRMT7 a 1.1-kb fragment with primers PRMT7-N1 and PRMT7-ΔC1 (5′-CTC TCC TCA CCG CGG CCG CTT CAA GAG CAG GTG AGC CTG-3′), which introduces a single N375K mutation to place a NotI site at the 3′ end of the fragment for the purpose of cloning. The PCR product was digested with SalI and NotI and ligated into pGEX(SN). The plasmid pGEX-PRMT7ΔN was constructed by PCR amplification of pGEX-PRMT7 with primers PRMT7-ΔN1 (5′-CTA GTG TCG ACC ATG TTT GGA GAG ATC AAT GAC CAG-3′) and PRMT7-C1, resulting in a 950-bp fragment. PCR fragments were digested with SalI and NotI and ligated into pGEX(SN). Purification of GST-GAR, GST-PRMT1, GST-PRMT7, GST-PRMT7ΔC, and GST-PRMT7ΔN—GST-GAR and GST-PRMT1 were constructed as described previously (11Lin W.J. Gary J.D. Yang M.C. Clarke S. Herschman H.R. J. Biol. Chem. 1996; 271: 15034-15044Abstract Full Text Full Text PDF PubMed Scopus (386) Google Scholar, 13Gary J.D. Lin W.J. Yang M.C. Herschman H.R. Clarke S. J. Biol. Chem. 1996; 271: 12585-12594Abstract Full Text Full Text PDF PubMed Scopus (179) Google Scholar). GST-GAR, GST-PRMT1, GST-PRMT7, GST-PRMT7ΔC, and PRMT7ΔN were overexpressed in Escherichia coli DH5α cells (Invitrogen) by induction with 0.4 mm isopropyl-β-d-thiogalactopyranoside. Cells were lysed in the presence of 100 μm phenylmethylsulfonyl fluoride with seven 20-s sonicator pulses (50% duty; setting 4) on ice with a Sonifier cell disrupter W-350 (Smith-Kline Corp.). The resulting lysate was centrifuged for 40 min at 23,000 × g at 4 °C. The protein was then purified from extracts by binding to glutathione-Sepharose 4B beads (Amersham Biosciences) according to the manufacturer's instructions; the GST-fusion proteins were eluted with 30 mm glutathione, 50 mm Tris-HCl, pH 7.5, and 120 mm NaCl at protein concentrations of 0.1 to 0.2 mg/ml. In Vitro Labeling of MBP, Histone H2A, GST-GAR, Peptide R1, and Peptide R2 and Chemical Analysis of the Methylated Species—10 μg of myelin basic protein (MBP) (purified from bovine brain, lyophilized powder; Sigma), 10 μg of histone H2A (purified from calf thymus, Roche Applied Science), 10 μg GST-GAR, 52 μg peptide R1 (GGPGGRGGPG-NH2, California Peptide Research, Inc.) or 26.5 μg of peptide R2 (acetylGGRGG-NH2, California Peptide Research, Inc.) was incubated with 2 μg of GST-PRMT7. 52 μg of peptide R1 or 26.5 μg of peptide R2 were incubated with 2 μg of PRMT7ΔC or PRMT7ΔN. Sodium phosphate buffer (pH 7.5) was added to all reactions to a final concentration of 100 mm. Reactions were initiated by the addition of 3 μl of S-adenosyl-l-methyl-3Hmethionine (3HAdoMet, Amersham Pharmacia Biotech; 72.0–79.0 Ci/mmol; 13–14 μm) in a final volume of 60 μl. Reactions were allowed to proceed at 37 °C for 1 h. As a control, 2 μg of GST-GAR was added to 2 μg of GST-PRMT1 and sodium phosphate buffer (pH 7.5) for a final concentration of 100 mm and incubated at 37 °C for 30 min with 3 μlof3HAdoMet in a final volume of 30 μl. Reactions were stopped by freezing on dry ice. The in vitro reactions for MBP, histone H2A, and GST-GAR were mixed with 20 μg of bovine serum albumin as a carrier protein and an equal volume of 25% (w/v) trichloroacetic acid in a 6 × 50-mm glass vial and incubated at room temperature for 30 min. The precipitated protein was then centrifuged at 4000 × g for 30 min at 25 °C, the supernatant was drawn off and discarded, and the pellets were allowed to air dry. Acid hydrolysis was then carried out on these reactions in a water Pico-Tag Vapor-Phase apparatus in vacuo for 20 h at 110 °C using 200 μl of 6 N HCl. The in vitro reactions for peptides R1 and R2 were added to a 6 × 50-mm glass vial and dried by speed vacuum. 50 μl of 6 N HCl was added to each vial, and the samples were hydrolyzed in vacuo for 20 h at 110 °C. Hydrolyzed samples were resuspended in 50 μl of water and mixed with 1.0 μmol of each of the standard ω-NG-monomethylarginine (ω-MMA, acetate salt, Sigma) and asymmetric ω-NG,NG-dimethylarginine (ADMA, hydrochloride, Sigma) for amino acid analysis by column chromatography. 500 μl of citrate dilution buffer (0.2 m Na+, pH 2.2) was added to the hydrolyzed samples before loading onto a cation-exchange column (Beckman AA-15 sulfonated polystyrene beads; 0.9-cm inner diameter × column and eluted with sodium citrate buffer m Na+, pH at 1 at °C. Analysis of acid were determined by a as described previously J.D. Lin W.J. Yang M.C. Herschman H.R. Clarke S. J. Biol. Chem. 1996; 271: 12585-12594Abstract Full Text Full Text PDF PubMed Scopus (179) Google Scholar). in column was using a as an of The of was determined to be using a standard. Purification of Methylated Peptide R1 and Chemical Analysis of the Methylated μg of peptide R1 was added to 20 μg of GST-PRMT7 and incubated with 10 μlof3HAdoMet at 37 °C for h in a final volume of μl and a final concentration of 100 mm sodium reactions were stopped by freezing on dry ice. were then and dried in a apparatus and resuspended in 60 μl of An equal volume of acid was added to the reaction and out the proteins that were The was at × g for and the supernatant was onto a column column × at room temperature in A acid in a of 1 the was eluted with of water in using the and The column was at and were to the peptide were and to μl. were onto the column and eluted the as to the peptide were dried in a 6 × 50-mm glass 50 μl of 6 N HCl was added to each 6 × 50-mm glass vial, and acid hydrolysis was then carried out on the reactions in a water Pico-Tag Vapor-Phase apparatus in vacuo for 20 h at 110 °C. The hydrolyzed samples were resuspended in 50 μl of water and on a column as described with μg of GST-PRMT7, μg of GST-PRMT7ΔC, or 2 μg of were incubated with μm and mm in 50 mm sodium pH in a volume of 50 μl. In salt, Roche Sigma), Sigma) or were added to a final concentration of 100 were added to and incubated at 4 °C for 20 were to at using a the The reaction was stopped by the addition of 50 μl of buffer mm pH and and at 100 °C for min. were at for 4 h using a buffer on a with and 2 were with for 30 min and in and acid were with were dried at °C in vacuo and to at °C. The PRMT of enzymes amino acid the seven motifs and III M. Clarke S. Mol. Cell. 2003; 2: Full Text Full Text PDF PubMed Scopus (139) Google Scholar), and in other of the A. Yadav N. Lee J. Branscombe T.L. Clarke S. Bedford M.T. J. Biol. Chem. 2002; 277: 3537-3543Abstract Full Text Full Text PDF PubMed Scopus (278) Google Scholar, L. EMBO J. 2000; PubMed Scopus Google Scholar). A of the GenBank amino acid using the T.L. J. Z. W. D. Nucleic Acids Res. PubMed Scopus Google for that known PRMT enzymes identified a full-length cDNA as of the of L. Proc. Natl. Acad. Sci. U. S. A. 2002; PubMed Scopus Google Scholar). This cDNA is encoded by a gene on human chromosome 16q22.1 and a acid protein We the sequence of this now designated PRMT7, with the previously described human in PRMT7, although seven motifs I and I with other appears at motifs II and PRMT7 additional to only the PRMT in the in the motifs I and I and at two the and motifs II and and the THW and at residues L. EMBO J. 2000; PubMed Scopus Google Scholar, 2003; Full Text Full Text PDF PubMed Scopus Google Scholar). although the two residues are at the in the loop, is only in the residues in that are in of the other PRMT enzymes. PRMT7 is unique these enzymes in that the of the THW is by an acid in A of the GenBank with the human PRMT7 sequence in a of the the the and the However, we in the and or in A plasmid a fusion construct of and the full-length sequence of PRMT7 was expressed in coli cells and purified by chromatography, as described A single of was with that for to the PRMT7 We if the GST-PRMT7 fusion protein to the GST-PRMT7 was to at in the presence of The reaction was then by and by As shown in a radiolabeled was at to the GST-PRMT7 fusion In addition of the and substrate and product the whereas the addition of the An was with the substrate MBP, and GST-GAR have been used as methyl-accepting substrates to and J. Gary J.D. Clarke S. Herschman H.R. J. Biol. Chem. 1998; 273: 16935-16945Abstract Full Text Full Text PDF PubMed Scopus (270) Google Scholar, T.L. Frankel A. Lee J.H. Cook J.R. Yang Z. Pestka S. Clarke S. J. Biol. Chem. 2001; 276: 32971-32976Abstract Full Text Full Text PDF PubMed Scopus (292) Google Scholar, Kim S. J. Biol. Chem. Full Text PDF PubMed Google Scholar). To the activity of PRMT7, the GST-fusion protein was incubated with GST-GAR, MBP, or histone H2A in the presence of Protein reaction products were precipitated with trichloroacetic to amino acid and by high-resolution amino acid cation-exchange chromatography with of asymmetric and No protein arginine activity was GST-GAR, MBP, or histone H2A was used as a substrate for GST-PRMT7. However, activity was in a GST-GAR was used as a substrate for GST-PRMT1 these PRMT7 these substrates as PRMT7 have a substrate specificity that is from the other known arginine methyltransferases. The R1 from the site for PRMT has been used to activity in cells and in mammalian with the activity of (11Lin W.J. Gary J.D. Yang M.C. Clarke S. Herschman H.R. J. Biol. Chem. 1996; 271: 15034-15044Abstract Full Text Full Text PDF PubMed Scopus (386) Google Scholar, J. Aswad D.W. J. Biol. Chem. Full Text PDF PubMed Google Scholar). PRMT7 was to methylate the protein GST-GAR, we to PRMT7 be able to methylate the site in a peptide Reactions with peptide R1 peptide R1 GST-PRMT7, or GST-PRMT7 were incubated with The R1 peptide was then separated from other reaction by was found to with peptide R1 on the column in all reaction not However, the to the peptide were in each and then by high-resolution amino acid we found to with the ω-NG-monomethylarginine only in the reaction GST-PRMT7 and peptide R1, and not in the reactions PRMT7 or peptide GST-PRMT7 is able to methylate a we to see PRMT7 methylate free We were by the presence of free ω-NG-monomethylarginine and asymmetric ω-NG,NG-dimethylarginine in and as of the J. P. Res. 1999; PubMed Scopus Google Scholar, J. Biol. Chem. 2002; 277: Full Text Full Text PDF PubMed Scopus Google Scholar). arginine was incubated with GST-PRMT7 and Analysis of the reaction by high-resolution chromatography not the presence of arginine suggesting that free arginine is in a substrate of PRMT7 not PRMT7 appears to have from a gene duplication event resulting in two PRMT domains The of PRMT7 shown in 1 (amino acids contains a PRMT domain that is similar to the of PRMT5, sequence and is similar to PRMT2 and PRMT6 The of PRMT7 (amino acids sequence with and sequence with the of the protein The of PRMT7 in the AdoMet-binding I the and other PRMT although it has an THW loop. To the PRMT7 domains can and fusion proteins and were purified from coli and for arginine When peptide R1 or peptide R2 was used as a fusion protein activity, whereas the full-length construct was able to catalyze the formation of ω-NG-monomethylarginine in both peptides. using were with and We found that was able to with 3HAdoMet, whereas was not not As with the full-length the addition of AdoMet, AdoHcy, and the of to GST-PRMT7, whereas the addition of of PRMT7 or domain to a of Peptide R1 or peptide R2 were incubated with and GST-PRMT7 (amino acids or (amino acids as described reactions were dried and methylated were and the was using chromatography, as described was determined by a of other with μl of water in of for 3 min. The amino acid were using a with of other In a for that the cell to the Chinese hamster of PRMT7 was identified as a gene to a to a II (18Gros L. Delaporte C. Frey S. Decesse J. de Saint-Vincent B.R. Cavarec L. Dubart A. Gudkov A.V. Jacquemin-Sablon A. Cancer Res. 2003; 63: 164-171PubMed Google Scholar). of PRMT7 from the Chinese hamster cell cells were shown to methylate the methylated product was not identified in this it was to be at an arginine from the sequence with other PRMT enzymes (18Gros L. Delaporte C. Frey S. Decesse J. de Saint-Vincent B.R. Cavarec L. Dubart A. Gudkov A.V. Jacquemin-Sablon A. Cancer Res. 2003; 63: 164-171PubMed Google Scholar). However, we that human GST-PRMT7 purified from coli not activity is used as a the human and hamster proteins at it is that this is However, it is to out the that the activity with the hamster enzyme be to a PRMT activity in the PRMT7, or to the presence of additional or J. Gary J.D. Clarke S. Herschman H.R. J. Biol. Chem. 1998; 273: 16935-16945Abstract Full Text Full Text PDF PubMed Scopus (270) Google Scholar, T.L. Frankel A. Lee J.H. Cook J.R. Yang Z. Pestka S. Clarke S. J. Biol. Chem. 2001; 276: 32971-32976Abstract Full Text Full Text PDF PubMed Scopus (292) Google Scholar). In this we that GST-PRMT7 is an arginine that can catalyze the formation of ω-NG-monomethylarginine in although its have yet to be The that PRMT7 has an duplication of domains and is incapable of methylating the PRMT substrates GST-GAR, MBP, or histone H2A distinguishes it from all other known arginine methyltransferases. is not PRMT7 be a enzyme in or be for yet to be determined PRMT7 be of the addition of a group to an arginine in an substrate to the asymmetric of type I enzymes or the dimethylarginine residues of type II enzymes. was previously that a enzymes that catalyze type I type II methylation reactions is the of the at the to in (15Branscombe T.L. Frankel A. Lee J.H. Cook J.R. Yang Z. Pestka S. Clarke S. J. Biol. Chem. 2001; 276: 32971-32976Abstract Full Text Full Text PDF PubMed Scopus (292) Google Scholar, L. EMBO J. 2000; PubMed Scopus Google Scholar). the type I PRMT1, PRMT3, PRMT4, and PRMT6 enzymes a and the type II enzyme contains a the the methylation reaction to on the In the of PRMT7, the is an suggesting the of type II