AB3341 Sigma-AldrichAnti-PRMT3 NT Antibody

Protein arginine methyltransferases (PRMTs) regulate mRNA processing and maturation by modulating the activity of RNA-binding proteins through methylation. The cDNA for human PRMT1 (HRMT1L2) was recently identified. In this paper, we describe the complete genomic organization of the human PRMT1 gene (GenBank Accession No. AF222689), together with its precise chromosomal localization in relation to other neighboring genes. We have also examined its expression in a total RNA panel of 26 human tissues, the BT-474 breast carcinoma cell line, and 16 breast tumors. PRMT1, which spans 11.2 kb of genomic sequence on chromosome 19q13.3, is located in close proximity to the IRF3 and RRAS genes and is transcribed in the opposite direction. It is formed of 12 coding exons and 11 intervening introns, and shows structural similarity to other PRMT genes. Three PRMT1 isoforms exist as a result of alternative mRNA splicing. Amino acid sequence comparison of the splicing variants indicates that they are all enzymatically active methyl transferases, but with different N-terminal hydrophobic regions. PRMT1 expression was detected in a variety of tissues. We have shown that the relative prevalence of alternatively spliced forms of PRMT1 is different between normal and cancerous breast tissues. Although PRMT1 was not found to be hormonally regulated by steroid hormones in breast cancer cells, our results suggest that two variants of PRMT1 are down regulated in breast cancer.

S-Adenosyl-l-methionine-dependent protein arginine N-methyltransferases (PRMTs) catalyze the methylation of arginine residues within a variety of proteins. At least four distinct mammalian family members have now been described, including PRMT1, PRMT3, CARM1/PRMT4, and JBP1/PRMT5. To more fully define the physiological role of PRMT3, we characterized its unique putative zinc-finger domain and how it can affect its enzymatic activity. Here we show that PRMT3 does contain a single zinc-finger domain in its amino terminus. Although the zinc-liganded form of this domain is not required for methylation of an artificial substrate such as the glutathione S-transferase-fibrillarin amino-terminal fusion protein (GST-GAR), it is required for the enzyme to recognize RNA-associated substrates in RAT1 cell extracts. The recombinant form of PRMT3 is inhibited by high concentrations of ZnCl(2) as well as N-ethylmaleimide, reagents that can modify cysteine sulfhydryl groups. We found that we could distinguish PRMT family members by their sensitivity to these reagents; JBP1/PRMT5 and Hsl7 methyltransferases were inhibited in a similar manner as PRMT3, whereas Rmt1, PRMT1, and CARM1/PRMT4 were not affected. We were also able to define differences in these enzymes by their sensitivity to inhibition by Tris and free arginine. Finally, we found that the treatment of RAT1 cell extracts with N-ethylmaleimide leads to a loss of the major PRMT1-associated activity that was immune to inhibition under the same conditions as a GST fusion protein. These results suggest that native forms of PRMTs can have different properties than their GST-catalytic chain fusion protein counterparts, which may lack associated noncatalytic subunits.