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Ca2+ plays a critical role in intracellular signaling. Intracellular Ca2+ levels are tightly controlled by continuos removal of Ca2+ via ATP-driven Ca2+ pump in the endoplasmic reticulum and plasma membrane, and Ca2+ transport system, the Na+/Ca2+ exchangers (NCX), in the plasma membrane. NCX can move Ca2+ either into or out of cells, depending on the net Na+, Ca2+, and K+ gradient across the membrane. In most cells, 3 Na+ are exchanged for 1 Ca2+. In mammals, at least 5 distinct genes code for the exchangers: Three NCX (NCX1, NCX2, and NCX3), and two in the NCKX family (NCKX1 and NCKX2). NCX share significant sequence homology (~70%), display 11 TM domains, a large central, intracellular hydrophilic regulatory loop between TM5 and 6, extracellular N-terminus and cytoplasmic C-terminus. The N-terminal signal peptide is cleaved off from the mature exchanger protein.
NCX contains a highly basic region in the large hydrophilic, intracellular loop called XIP (Exchange inhibitory peptide; RRLLFYKYVYKRYRAGKQRG 20 aa), that inhibits Na-Ca+ exchange in cardiac sarcolemmal vesicles and in other cells. Little or no sequence identity is found between the NCX and the Ca-pump. However, XIP also inhibits the Ca pumps with more or less same efficiency as C28R2 peptide sequence (LRRGQILWFRGLNRIQTQIRVVKAFRSS, 28 aa) corresponding to the autoinhibitory domain of the Ca-pump.
NCX1 (rat 971 aa, human 970 aa, mouse 970 aa) is most prominently expressed in the heart where it plays a major role in excitation-contraction coupling, but is also present in most other tissues. Alternative spicing of NCX1/NACA1 produces numerous tissue specific isoforms (heart NACA1; Kidney NACA2, -3, and -7; brain NACA4-6). NCX2 (rat 921 aa) is restricted to brain and skeletal muscle. NCX3 (rat 927 aa) shares 73-75% with NCX1 and NCX2. It is predicted to have the same membrane topology as NCX1. Like NCX2, NCX3 is restricted to brain and muscle.
In vertebrate photoreceptors, some neurons, and certain other cells, 3 K+ are transported in the same direction as Ca2+, with coupling ratio of 4 Na+ to 1 Ca2+ plus 1 K+ by new class of exchangers called NCKX for K+-dependent Na/Ca+2 exchangers. NCKX share the general topology and functional properties of NCX proteins. Rod exchangers also contains a large hydrophilic segment at the its N-terminus that is not found in NCX. NCKX1 (human 1099/1081 aa, bovine 1199 aa) is expressed in retinal rod cells. NCKX2 (rat 670 aa) shares 80% identity with NCKX1. The two hydrophilic loops are also much shorter in NKKX2 than in NCKX1, accounting largely for the difference between the size of the two proteins. NCKX2 is expressed in various regions of the brain (striatum, parietal cortex, cerebellum, hippocampus, and thalamus).
ADI has produced highly specific rabbit antibodies to NCX1-3, NCKX1-2, and also to the XIP and C28R2 using peptide sequences specific to each protein.
 

m=mouse; r=rat; h=human; ch=chicken; f=frog; ~CT or ~NT=near C or N-terminus. EC=Extracellular; CP=Cytoplasmic domain;

"Neat Antisera" are the unpurified antiserum and it is suitable for ELISA and Western.
"Affinity pure" antibodies have been over the antigen-affinity column and recommended for immunohistochemical applications.
"Control peptides" can not be used for Western as they are very short peptides. They are intended for ELISA or antibody competition studies.

List of publications using ADI's Antibodies to various NCXs related items

Product Authors Year of Pub Title Journal Western IHC IP Other tech Comments
C28R2
Zhong, Ning 2001 Roles for Mitochondrial and Reverse Mode Na+/Ca2+ Exchange and the Plasmalemma Ca2+ ATPase in Post-Tetanic Potentiation at Crayfish Neuromuscular Junctions,J. Neurosci. 21: 9598-9607, peptides

CASR
Wang R, 2003, Calcium and polyamine regulated calcium-sensing receptors in cardiac tissues Eur. J. Biochem., Jun 2003; 270: 2680 - 2688, WB, IHC , rat mycocytes

NCX1
Unlap MT 2003 Na+/Ca2+ Exchanger. Target for Oxidative Stress in Salt-Sensitive Hypertension Hypertension, 42, 363-368 WB OK-pth cells

NCX1
Okafor M 2003 Sodium-calcium exchange influences the response to endothelin-1 in lens epithelium Cell Calcium 34, Issue 3, September 2003, Pages 231-240 WB IHC 4% PF ,Bovine eye lens, Ab blocking with CP

XIP
Zhong, Ning 2001 Roles for Mitochondrial and Reverse Mode Na+/Ca2+ Exchange and the Plasmalemma Ca2+ ATPase in Post-Tetanic Potentiation at Crayfish Neuromuscular Junctions, J. Neurosci. 21: 9598-9607, peptides

Notes: Antibodies usage is indicated in the following techniques: WB=Western Blot ; IHC-Immunohistochmistry; IP=Immunoprecipition; Flow=Flow cytometry

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