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Updated: Jun 26, 2026

Construction of Model Lipid Membranes Incorporating G-protein Coupled Receptors (GPCRs)
Published on: February 5, 2022
A novel lipid binding protein is a factor required for MgATP stimulation of the squid nerve Na+/Ca2+ exchanger
Graciela Berberián1, Mariana Bollo, Guillermo Montich
1Laboratorio de Biofísica, Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC-CONICET), Casilla de Correo 389, 5000 Córdoba, Argentina.
Abstract:
Here we identify a cytosolic factor essential for MgATP up-regulation of the squid nerve Na(+)/Ca(2+) exchanger. Mass spectroscopy and Western blot analysis established that this factor is a member of the lipocalin super family of lipid binding proteins of 132 amino acids in length. We named it Regulatory protein of the squid nerve sodium calcium exchanger (ReP1-NCXSQ). ReP-1-NCXSQ was cloned, over expressed and purified. Far-UV circular dichroism and infrared spectra suggest a majority of beta-strand in the secondary structure. Moreover, the predicted tertiary structure indicates ten beta-sheets and two short alpha-helices characteristic of most lipid binding proteins. Functional experiments showed that in order to be active ReP1-NCXSQ must become phosphorylated in the presence of MgATP by a kinase that is Staurosporin insensitive. Even more, the phosphorylated ReP1-NCXSQ is able to stimulate the exchanger in the absence of ATP. In addition to the identification of a new member of the lipid binding protein family, this work shows, for the first time, the requirement of a lipid binding protein for metabolic regulation of an ion transporting system.
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