SAM (sterile alpha motif) domain repeat 2 of liprin-alpha proteins is a protein-protein interaction domain. Liprin-alpha proteins contain three copies (repeats) of SAM domain. They may form heterodimers with liprin-beta proteins through their SAM domains. They participate in mammary gland development and in axon guidance; in particular, liprin-alpha is involved in formation of the presynaptic active zone.