SAM (sterile alpha motif) domain repeat 1 of liprin-beta1,2 proteins is a protein-protein interaction domain. Liprin-beta protein contain three copies (repeats) of SAM domain. They may form heterodimers with liprins-alpha through their SAM domains. It was suggested based on bioinformatic approaches that the second SAM domain of liprin-beta is potentially able to form polymers. 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.