Identification and characterization of a new human gene encoding a small protein with high homology to the proline-rich region of the SH3BGR gene.

As part of an effort to identify genes potentially involved in the Down Syndrome pathogenesis, in this paper we report the identification and characterization of a new human gene (named SH3BGRL), which shows a high homology to the SH3BGR gene, previously mapped to the Down Syndrome region of chromosome 21. The SH3BGRL gene encodes for a small protein of 114 amino acids, sharing 60% identity and 84% conservation on the amino acid level with themiddle, proline-rich region of the SH3BGR gene and containing a similar SH3 (Scr homology 3) binding motif. The SH3BGRL and the proline-rich region of SH3BGR proteins appear to be highly conserved, sharing 95 and 98% identity, respectively, with the mouse homologues. A 1.9 kb transcript of the SH3BGRL gene has been found in all the tissues examined, in contrast with the expression pattern of the SH3BGR gene which is transcribed only in heart and skeletalmuscle. The SH3BGR gene and its homologue, SH3BGRL, could be members of a new family of genes containing a highly conserved proline-rich functional domain. The SH3BGRL gene has been mapped by fluorescent in situ hybridization to Chromosome Xq13.3.