کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1945142 | 1053254 | 2009 | 8 صفحه PDF | دانلود رایگان |
Here we identify a cytosolic factor essential for MgATP up-regulation of the squid nerve Na+/Ca2+ 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 β-strand in the secondary structure. Moreover, the predicted tertiary structure indicates ten β-sheets and two short α-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.
Journal: Biochimica et Biophysica Acta (BBA) - Biomembranes - Volume 1788, Issue 6, June 2009, Pages 1255–1262