title: Localization of plasma membrane CD38 is domain specific in rat hepatocyte.
abstract: CD38 is a 42- to 45-kDa type II transmembrane glycoprotein with the ability to synthesize cADPR, a metabolite with potent calcium mobilizing properties independent of IP(3). We report here the primary characterization and localization of CD38 in the plasma membrane fraction of rat hepatocyte. Western blot analysis of a partially purified plasma membrane fraction with a panel of polyclonal antibodies against CD38 detected a 42- to 45-kDa protein band which is characteristic of CD38. ADP-ribosyl cyclase activity was found to be present in the plasma membrane fraction, indicating the presence of functionally active CD38. Subfractionation of the plasma membrane to the sinusoidal and bile canalicular membrane fractions showed the presence of ADP-ribosyl cyclase activity in both fractions with the sinusoidal membrane fraction having a 10-fold higher specific activity than the bile canalicular membrane fraction. Immunohistochemical staining with the same panel of polyclonal antibodies showed exclusive differential spatial localization to both the nuclei and sinusoidal domain of the plasma membrane. It is possible that the different spatial distribution of CD38 in the rat hepatocyte might be responsible for its myriad of previously known functional roles.
authors.affiliation: Faculty of Medicine, National University of Singapore, 10, Kent Ridge Crescent, S119260, Singapore.
authors.forename: K M
authors.initials: KM
authors.lastname: Khoo
authors.forename: C F
authors.initials: CF
authors.lastname: Chang
mesh_terms: D036541:ADP-ribosyl Cyclase; D051997:ADP-ribosyl Cyclase 1; D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology* / Q000276:immunology*; D002467:Cell Nucleus / Q000201:enzymology / Q000276:immunology; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D008099:Liver / Q000201:enzymology* / Q000276:immunology*; D008297:Male; D008562:Membrane Glycoproteins; D009244:NAD+ Nucleosidase / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000906:Antibodies; D015703:Antigens, CD; D000943:Antigens, Differentiation; D007527:Isoenzymes; D008562:Membrane Glycoproteins; D036541:ADP-ribosyl Cyclase; C498156:Cd38 protein, rat; D009244:NAD+ Nucleosidase; D051997:ADP-ribosyl Cyclase 1