SAM (sterile alpha motif) domain repea t3 of liprin-beta1,2 proteins is a protein-protein interaction domain. Liprin-beta proteins contain three copies (repeats) of SAM domain. They may form heterodimers with liprin-alpha proteins through their SAM domains. Liprins were originally identified as LAR (leukocyte common antigen-related) transmembrane protein-tyrosine phosphatase-interacting proteins. They participate in mammary gland development, in axon guidance, and in the maintenance of lymphatic vessel integrity.