Localization, genomic organization, and alternative transcription of a novel human SAM-dependent methyltransferase...

As part of our studies to identify the gene responsible for hereditary gingival fibromatosis, GINGF (OMIM 135300), we have identified and cloned a novel human gene that contains the highly conserved methyltransferase domain characteristic of S-adenosylmethionine-dependent methyltransferases. We localized this gene (C2orf8 encoding 288L6 SAM-methyltransferase) to chromosome 2p22-->p21 by FISH, and sublocalized it to BAC RP11 288L6 flanked by D2S2238 and D2S2331. Computational analysis of aligned ESTs identified ten exons in the hypothetical C2orf8 gene. Results of RACE analyses in placenta identified multiple transcripts of this gene with heterogeneity at the 5'-UTR. Alternative transcription and tissue specific expression of C2orf8 were detected by RT-PCR and Northern blot analyses. C2orf8 is expressed in a variety of tissues including brain, colon, gingiva, heart, kidney, liver, lung, placenta, small intestine, spleen, and thymus. Open reading frame analysis of the alternative transcripts identified a shared coding region spanning exons 6-10. This ORF consists of 732 nucleotides encoding a putative 244 amino acid protein. Bioinformational searches of both C2orf8 and the putative protein product identified three methyltransferase motifs conserved across many prokaryotic and eukaryotic species. Sequence analyses of C2orf8 excluded coding region mutations as causative of GINGF.