Abstract
CD38 is a transmembrane glycoprotein involved as an orphan receptor in many physiological processes of lymphocytes. It is also a bifunctional enzyme that catalyzes at its ectocellular domain the synthesis from NAD+ (cyclase) and the hydrolysis (hydrolase) of the calcium-mobilizing metabolite cyclic ADP-ribose (cADPR). A still unexplained paradox concerns the relationship between ectocellular localization of CD38 and intracellular calcium-releasing activity of its intermediate product cADPR. Incubation of CD38+ human Namalma B cells with external NAD+ elicited extensive membrane down-regulation of CD38 and its internalization in non-clathrin-coated vesicles. Since the internalized CD38 was demonstrated to be enzymatically active, this NAD+-dependent process is a hitherto unrecognized means for shifting cADPR metabolism from the cell surface to the intracellular environment.
Original language | English |
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Pages (from-to) | 327-332 |
Number of pages | 6 |
Journal | FEBS Letters |
Volume | 396 |
Issue number | 2-3 |
DOIs | |
Publication status | Published - Nov 4 1996 |
Keywords
- ADP-ribosyl cyclase
- CD38
- Ectoenzyme
- Endocytosis
- NAD
ASJC Scopus subject areas
- Biochemistry
- Biophysics
- Molecular Biology