GRAM domain-containing protein 2A (GRAMD2A)

GRAM domain-containing protein 2A (GRAMD2A) is a mammalian membrane protein characterized by a GRAM domain and a transmembrane region, anchoring it to the endoplasmic reticulum. It operates at membrane contact sites, specifically tethering the ER to the plasma membrane via direct binding of its GRAM domain to phosphatidylinositol 4,5-bisphosphate in the plasma membrane. GRAMD2A is essential for the recruitment of stromal interaction molecule 1 (STIM1), facilitating the store-operated calcium entry (SOCE) pathway, which is a critical component of intracellular calcium regulation. Unlike other LAM family members, GRAMD2A lacks a VASt (sterol transfer) domain and is primarily associated with spatial organization of ER-plasma membrane contact sites destined for SOCE. It marks a subset of highly specialized ER-PM domains and participates in calcium signaling through organizational rather than enzymatic or receptor-mediated functions. No evidence currently positions GRAMD2A as a major therapeutic target or biomarker. It is structurally critical for calcium homeostasis but is functionally redundant with other ER-PM tethers, and absence of GRAMD2A leads to compensatory mechanisms within the cell, without dramatic functional loss or disease association.

Other names

GRAMD2AGRAMD2GRAM domain containing 2AGRAM domain-containing protein 2A