Rabphilin-3AL (rabphilin-3A-like), also known as RPH3AL or NOC2, is a cytoplasmic Rab GTPase effector. It contains one FYVE-type zinc finger and one Rab-binding (RBD) domain, but unlike its related protein, rabphilin-3A, rabphilin-3AL does not contain any C2 domains. Rabphilin-3AL is expressed in a variety of tissues, with highest levels found in kidney, skeletal muscle, pancreas, liver, ovary, stomach, heart and thyroid. It is believed to play a role regulating calcium-dependent secretory vesicle exocytosis in endocrine and exocrine cells. Via its RBD domain, rabphilin-3AL is capable of binding Rab 27a and, through this interaction, rabphilin-3AL is recruited to dense-core vesicles. With lower affinity, rabphilin-3AL can also bind Rab 3 and Rab 8 with its RBD domain. Through an interaction with Rab 3, rabphilin-3AL can inhibit G-protein signaling in endocrine pancreas and positively regulate insulin secretion. Rabphilin-3AL knockout mice display accumulation of secretory granules and irregular shape in exocrine cells.
Function: Rab GTPase effector involved in the late steps of regulated exocytosis, both in endocrine and exocrine cells (By similarity). Acts as a potential RAB3B effector protein in epithelial cells.
Subunit: Recruited to dense-core vesicles through specific interaction with RAB27A in endocrine cells. Interacts with RAB3A, RAB3B, RAB3C and RAB3D. Interacts with ZYX.
Subcellular Location: Cytoplasm. Cytoplasmic vesicle, secretory vesicle membrane. Recruited to the vesicle membrane in a GTP-and RAB3B-dependent manner in epithelial cells.
Tissue Specificity: Moderate to high levels of expression in thyroid, ovary, stomach, heart, pancreas, skeletal muscle, kidney and liver. Also detected in epithelial cells.
