MW: 51,335 Da. Western Blot Positive Control Serine incorporator 5Restriction factor required to restrict infectivity of gammaretroviruses, such as HIV-1: acts by inhibiting early step of viral infection and impairing the ability of the viral particle to translocate its content to the cytoplasm (PubMed:26416733, PubMed:26416734). Enhances the incorporation of serine into phosphatidylserine and sphingolipids. May play a role in providing serine molecules for the formation of myelin glycosphin