SEMG1 is the predominant protein in semen. The 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. Recombinant human SEMG1 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.