Isolation and Structure Analysis of a SH3 Domain Protein from Monascus purpureus

SH3 (Src homology 3) domain is a small modules units (similar to 60 amino acids) that are important for the generation of protein-protein interactions in cellular signal transduction pathways. SH3 domains commonly bind to proline-rich sequences. Here, we explore the SH3 domain proteins in Monascus purpureus. A M. purpureus cDNA library was constructed, and the MpSH3 cDNA was isolated from the cDNA library by sequencing method. The cDNA was 1239 bp in length, contains a predicted 744 bp ORF that encodes 247 amino acids, the gene was designated MpSH3. The deduced amino acid sequence showed homology with SH3 domain proteins of fungi. A three-dimensional model of MpSH3 was built using homology modeling method. The 3D structure model of MpSH3 indicated that the domain is 52 residues long and is composed of five beta-strands, and has canonical RT, N-Src loops and 310-helix. The structure analysis implicated that the MpSH3 protein can mediate protein-proteins via recognition of proline-rich peptides.