Semenogelin I (SEMG1)

Semenogelin I is the predominant protein in semen. The encoded secreted protein is involved in the formation of a gel matrix that encases ejaculated spermatozoa. The prostate-specific antigen (PSA) protease processes this protein into smaller peptides, with each possibly having a separate function. The proteolysis process breaks down the gel matrix and allows the spermatozoa to move more freely. Two transcript variants encoding different isoforms have been found for this gene.An open reading frame of 1,386 nucleotides encoded a signal peptide and a mature protein of 439 amino acid residues, in which residues 85 to 136 were identical with a previously characterized semenogelin fragment. An abundant seminal vesicular mRNA transcript of 1.8 kb codes for semenogelin.