title: Phospholipase C-gamma binds directly to the Na+/H+ exchanger 3 and is required for calcium regulation of exchange activity.
abstract: Multiple studies suggest that phospholipase C-gamma (PLC-gamma) contributes to regulation of sodium/hydrogen exchanger 3 (NHE3) in the small intestine, although the mechanism(s) for this regulation remain unknown. We demonstrate here that PLC-gamma binds directly to the C terminus of NHE3 and exists in similar sized multiprotein complexes as NHE3. This binding is dynamic and decreases with elevated [Ca(2+)](i). The PLC-gamma-binding site in NHE3 was identified (amino acids 586-605) and shown to be a critical regulatory domain for protein complex formation, because when it is mutated, NHE3 binding to PLC-gamma as well as NHERF2 is lost. An inhibitory peptide, which binds to the Src homology 2 domains contained in PLC-gamma without interrupting binding of PLC-gamma to NHE3, was used to probe a non-lipase-dependent role of PLC-gamma. In the presence of this peptide, carbachol-stimulated calcium inhibition of NHE3 was lost. These results mirror previous studies with the transient receptor potential channel and suggest that PLC-gamma may play a common role in regulating the cell-surface expression of ion transporters.
authors.affiliation: Division of Gastroenterology and Hepatology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Zachos
authors.forename: Damian B
authors.initials: DB
authors.lastname: van Rossum
authors.forename: Xuhang
authors.initials: X
authors.lastname: Li
authors.forename: Gabriela
authors.initials: G
authors.lastname: Caraveo
authors.forename: Rafiquel
authors.initials: R
authors.lastname: Sarker
authors.forename: Boyoung
authors.initials: B
authors.lastname: Cha
authors.forename: Sachin
authors.initials: S
authors.lastname: Mohan
authors.forename: Stephen
authors.initials: S
authors.lastname: Desiderio
authors.forename: Randen L
authors.initials: RL
authors.lastname: Patterson
authors.forename: Mark
authors.initials: M
authors.lastname: Donowitz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D001896:Boron Compounds / Q000737:chemistry; D018938:Caco-2 Cells; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D002460:Cell Line; D006801:Humans; D047468:Immunoprecipitation; D017136:Ion Transport / Q000187:drug effects; D007476:Ionophores / Q000494:pharmacology; D008969:Molecular Sequence Data; D009154:Mutation; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology; D051966:Phospholipase C gamma / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D011817:Rabbits; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000378:metabolism*
chemical_list: C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D001896:Boron Compounds; D007476:Ionophores; D010455:Peptides; D010750:Phosphoproteins; C000613385:SLC9A3 protein, human; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers; C093376:sodium-hydrogen exchanger regulatory factor; D000001:Calcimycin; D002217:Carbachol; D051966:Phospholipase C gamma; D002118:Calcium