title: Calcineurin homologous protein isoform 2 (CHP2), Na+/H+ exchangers-binding protein, is expressed in intestinal epithelium.
abstract: The Na+/H+ exchangers (NHEs) comprise a family of membrane proteins that catalyze the electroneutral exchange of Na+ and H+. Calcineurin homologous protein (CHP) acts as a crucial cofactor for NHE activity through direct interaction with the carboxyl-terminal tail region of NHEs. We have cloned a new rat CHP isoform (rCHP2) and characterized the binding property to NHEs and the tissue distribution. rCHP2 binds to the juxtamembrane region of plasma membrane-type NHE isoforms (NHE1-5) in vivo and in vitro as well as rCHP1 (original rat CHP). Interestingly, CHP2 is predominantly expressed in the small and large intestine although rCHP1 shows relatively ubiquitous expression at both the mRNA and protein levels. In situ hybridization experiments demonstrated the abundant expression of CHP2 in the epithelial cell layer of villi of the small intestine in contrast with the expression of CHP1 in both the epithelial layer and connective tissues. These results suggest that CHP2 functions in the absorptive epithelium for the intestine with NHE(s).
authors.affiliation: Department of Biological Science, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan. hirokii@bio.sci.osaka-u.ac.jp
authors.forename: Hiroki
authors.initials: H
authors.lastname: Inoue
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Mana
authors.initials: M
authors.lastname: Nagita
authors.forename: Tomoyo
authors.initials: T
authors.lastname: Takai
authors.forename: Miho
authors.initials: M
authors.lastname: Masuda
authors.forename: Norihiro
authors.initials: N
authors.lastname: Nakamura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kanazawa
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides; D030161:Avian Proteins; D001483:Base Sequence; D002135:Calcium-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics*; D002460:Cell Line; D002522:Chlorocebus aethiops; D006224:Cricetinae; D023082:Defensins; D004285:Dogs; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009893:Opossums; D011485:Protein Binding / Q000502:physiology; D020033:Protein Isoforms / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D017923:Sodium-Hydrogen Exchangers / Q000096:biosynthesis* / Q000235:genetics*; D013552:Swine
chemical_list: D023181:Antimicrobial Cationic Peptides; D030161:Avian Proteins; C469743:CHP1 protein, human; D002135:Calcium-Binding Proteins; D023082:Defensins; D020033:Protein Isoforms; D017923:Sodium-Hydrogen Exchangers; C086738:gallinacin 2 protein, chicken