ESYT1
Domain
Anchored to the endoplasmic reticulum membrane by a transmembrane hairpin structure; both N-terminus and C-terminus are cytoplasmic.
The C2 domains mediate lipid and calcium binding. The N-terminal C2 domain binds calcium ions and is important for calcium-dependent lipid binding and interaction with membranes. Two calcium ions are bound at a high-affinity site and a third calcium ion is bound with lower affinity. May bind up to four calcium ions. In contrast, the second C2 domain apparently does not bind calcium (By similarity). The third C2 domain mediates interaction with membranes enriched in phosphatidylinositol 4,5-bisphosphate and is required for translocation to the cell membrane in response to increased cytosolic calcium levels (PubMed:23791178, PubMed:24183667).
The SMP-LTD domain is a barrel-like domain that can bind various types of glycerophospholipids in its interior (By similarity).
Function
Binds glycerophospholipids in a barrel-like domain and may play a role in cellular lipid transport (By similarity). Binds calcium (via the C2 domains) and translocates to sites of contact between the endoplasmic reticulum and the cell membrane in response to increased cytosolic calcium levels. Helps tether the endoplasmic reticulum to the cell membrane and promotes the formation of appositions between the endoplasmic reticulum and the cell membrane.
Post-translational modifications
Phosphorylated on Ser residues in insulin-treated adipocytes (in vitro); this promotes interaction with SLC2A4.
Sequence Similarities
Belongs to the extended synaptotagmin family.
Tissue Specificity
Widely expressed.
Cellular localization
- Endoplasmic reticulum membrane
- Multi-pass membrane protein
- Cell membrane
- Peripheral membrane protein
- Localizes primarily to the endoplasmic reticulum (PubMed:29469807). Recruited to sites of contact between the endoplasmic reticulum and the cell membrane in response to increased cytosolic calcium levels (PubMed:22250200, PubMed:29469807).
Alternative names
FAM62A, KIAA0747, MBC2, ESYT1, Extended synaptotagmin-1, E-Syt1, Membrane-bound C2 domain-containing protein