title: Hippocalcin in the olfactory epithelium: a mediator of second messenger signaling.
abstract: Intracellular Ca2+ plays an important role in a variety of second messenger cascades. The function of Ca2+ is mediated, in part, by Ca2+-binding proteins such as calmodulin, calretinin, calbindin, neurocalcin, recoverin, and visinin-like proteins (VILIPs). These proteins are highly expressed in rat olfactory receptor neurons (ORNs) and are localized to distinct intracellular regions. In the present study, we have identified another Ca2+-binding protein, hippocalcin, in the rat olfactory epithelium (OE). Olfactory/brain hippocalcin shows high sequence homology with hippocalcins expressed in mice and humans. Hippocalcin was predominantly localized to the olfactory cilia, the site of the initial events of olfactory signal transduction, and was found to regulate the activity of ciliary adenylate cyclases (ACs) and particulate guanylyl cyclases (GCs) in a Ca2+-dependent manner. These data indicate that hippocalcin is expressed in rat ORNs, and is likely to regulate second messenger cascades in a Ca2+-dependent manner.
authors.affiliation: Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: Alex
authors.initials: A
authors.lastname: Mammen
authors.forename: Phillis J
authors.initials: PJ
authors.lastname: Simpson
authors.forename: Alex
authors.initials: A
authors.lastname: Mamman
authors.forename: Jeanette P
authors.initials: JP
authors.lastname: Simpson
authors.forename: Alan
authors.initials: A
authors.lastname: Nighorn
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Imanishi
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Palczewski
authors.forename: Gabriele V
authors.initials: GV
authors.lastname: Ronnett
authors.forename: Cheil
authors.initials: C
authors.lastname: Moon
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D020013:Calcium Signaling; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000502:physiology*; D006162:Guanylate Cyclase / Q000378:metabolism; D051597:Hippocalcin; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000502:physiology*; D009831:Olfactory Mucosa / Q000378:metabolism*; D051381:Rats; D015290:Second Messenger Systems; D016415:Sequence Alignment
chemical_list: D002135:Calcium-Binding Proteins; C496691:HPCA protein, human; C496692:Hpca protein, mouse; C496693:Hpca protein, rat; D009419:Nerve Tissue Proteins; D051597:Hippocalcin; D006162:Guanylate Cyclase