This family consists of seminal vesicle autoantigen and prolactin-inducible (PIP) proteins. Seminal vesicle autoantigen (SVA) is specifically present in the seminal plasma of mice. This 19-kDa secretory glycoprotein suppresses the motility of spermatozoa by interacting with phospholipid. PIP, has several known functions. In saliva, this protein plays a role in host defense by binding to microorganisms such as Streptococcus. PIP is an aspartyl proteinase and it acts as a factor capable of suppressing T-cell apoptosis through its interaction with CD4.