title: Expression of cyclic ADP-ribose-synthetizing CD38 molecule on human platelet membrane.
abstract: CD38 is a cell surface molecule widely used as a marker for immature and activated lymphocytes. It has been recently shown that CD38 displays three enzymatic activities: hydrolysis of NAD+ to ADP-ribose, synthesis of cyclic ADP-ribose from NAD+, and hydrolysis of cyclic ADP-ribose to ADP-ribose. Thus, CD38 plays a key role in the synthesis of cyclic ADP-ribose, a calcium-mobilizing compound. We investigate here the expression and cellular localization of CD38 in human platelets using a specific monoclonal antibody. Results showed that CD38 is expressed by human platelet membranes. Moreover, we show that platelet CD38 possesses NAD glycohydrolase, ADP-ribose cyclase, and cyclic ADP-ribose hydrolase activities. This finding indicates that the calcium-mobilizing agent cyclic ADP-ribose can be synthetized by human platelets and raises the question about the possible role of CD38 expression and enzymatic activities in the signal transduction pathways leading to platelet activation.
authors.affiliation: Department of Biochemistry , University of Pavia, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Ramaschi
authors.forename: M
authors.initials: M
authors.lastname: Torti
authors.forename: E T
authors.initials: ET
authors.lastname: Festetics
authors.forename: F
authors.initials: F
authors.lastname: Sinigaglia
authors.forename: F
authors.initials: F
authors.lastname: Malavasi
authors.forename: C
authors.initials: C
authors.lastname: Balduini
mesh_terms: D036541:ADP-ribosyl Cyclase; D051997:ADP-ribosyl Cyclase 1; D000246:Adenosine Diphosphate Ribose / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000097:blood; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000097:blood*; D001792:Blood Platelets / Q000201:enzymology*; D002118:Calcium / Q000097:blood; D002384:Catalysis; D036563:Cyclic ADP-Ribose; D005434:Flow Cytometry; D006801:Humans; D008562:Membrane Glycoproteins / Q000097:blood*; D009699:N-Glycosyl Hydrolases / Q000097:blood*; D009244:NAD+ Nucleosidase / Q000097:blood*; D015539:Platelet Activation / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D008562:Membrane Glycoproteins; D036563:Cyclic ADP-Ribose; D000246:Adenosine Diphosphate Ribose; D009699:N-Glycosyl Hydrolases; D036541:ADP-ribosyl Cyclase; C498154:CD38 protein, human; D009244:NAD+ Nucleosidase; D051997:ADP-ribosyl Cyclase 1; D002118:Calcium