Hippocalcin in the olfactory epithelium: a mediator of second messenger signaling.
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.
Mammen
Alex
A
Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Simpson
Phillis J
PJ
Mamman
Alex
A
Simpson
Jeanette P
JP
Nighorn
Alan
A
Imanishi
Yoshikazu
Y
Palczewski
Krzysztof
K
Ronnett
Gabriele V
GV
Moon
Cheil
C
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
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