Sodium-hydrogen antiporter 3 regulator 1

Sodium-hydrogen antiporter 3 regulator 1 is a regulator of Sodium-hydrogen antiporter 3. It is encoded by the gene SLC9A3R1. It is also known as ERM Binding Protein 50 (EBP50) or Na+/H+ Exchanger Regulatory Factor (NHERF1). It is believed to interact via long-range allostery, involving significant protein dynamics.

Mechanism

Members of the ezrin (VIL2; MIM 123900)-radixin (RDX; MIM 179410)-moesin (MSN; MIM 309845) (ERM) protein family are highly concentrated in the apical aspect of polarized epithelial cells. These cells are studded with microvilli containing bundles of actin filaments, which must attach to the membrane to assemble and maintain the microvilli. The ERM proteins, together with merlin, the NF2 (MIM 607379) gene product, are thought to be linkers between integral membrane and cytoskeletal proteins, and they bind directly to actin in vitro. Actin cytoskeleton reorganization requires the activation of a sodium/hydrogen exchanger (SLC9A3; MIM 182307). SLC9A3R1 is an ERM-binding protein.[supplied by OMIM]

Sodium-hydrogen exchange regulatory cofactor 2

Sodium-hydrogen exchange regulatory cofactor NHE-RF2 (NHERF-2) also known as tyrosine kinase activator protein 1 (TKA-1) or SRY-interacting protein 1 (SIP-1) is a protein that in humans is encoded by the SLC9A3R2 (solute carrier family 9 isoform A3 regulatory factor 2) gene.

NHERF-2) is a scaffold protein that connects plasma membrane proteins with members of the ezrin/moesin/radixin family and thereby helps to link them to the actin cytoskeleton and to regulate their surface expression. It is necessary for cAMP-mediated phosphorylation and inhibition of SLC9A3. In addition, it may also act as scaffold protein in the nucleus.

Function

This regulatory protein (factor) interacts with a sodium/hydrogen exchanger NHE3 (SLC9A3) in the brush border membrane of the proximal tubule, small intestine, and colon that plays a major role in transepithelial sodium absorption. SLC9A3R2, as well as SLC9A3R1 and protein kinase A phosphorylation, may play a role in NHE3 regulation.