NAD+-dependent internalization of the transmembrane glycoprotein CD38 in human namalwa B cells

Elena Zocchi, Luisa Franco, Lucrezia Guida, Daniele Piccini, Carlo Tacchetti, Antonio De Flora

Research output: Contribution to journalArticlepeer-review

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 languageEnglish
Pages (from-to)327-332
Number of pages6
JournalFEBS Letters
Volume396
Issue number2-3
DOIs
Publication statusPublished - Nov 4 1996

Keywords

  • ADP-ribosyl cyclase
  • CD38
  • Ectoenzyme
  • Endocytosis
  • NAD

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

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