title: The human CD10 lacking an N-glycan at Asn(628) is deficient in surface expression and neutral endopeptidase activity.
abstract: BACKGROUND
  CD10, also known as neprilysin or enkephalinase exhibiting neutral endopeptidase (NEP) activity, is expressed by B-lineage hematopoietic cells as well as a variety of cells from normal tissues. It cleaves peptides such as cytokines to act for terminating inflammatory responses. Although CD10 molecules of the human pre-B-cell line NALM-6 have 6 consensus N-glycosylation sites, three of them are known to be N-glycosylated by X-ray crystallography.
  
  
  METHODS
  In order to investigate the role of N-glycans in the full expression of NEP activity, we modified N-glycans by treatment of NALM6 cells with various glycosidases or alter each of the consensus N-glycosylation sites by generating site-directed mutagenesis and compared the NEP activities of the sugar-altered CD10 with those of intact CD10.
  
  
  RESULTS
  CD10 of the human B-cell line NALM-6 was dominantly localized in raft microdomains and heterogeneously N-glycosylated. Although neither desialylation nor further degalactosylation caused defective NEP activity, removal of only a small part of N-glycans by treatment with glycopeptidase F under non-denaturing conditions decreased NEP activity completely. All of the three consensus sites of CD10 in HEK293 cells introduced with wild type-CD10 were confirmed to be N-glycosylated. Surface expression of N-glycan at Asn(628)-deleted CD10 by HEK293 cells was greatly decreased as well as it lost entire NEP activities.
  
  
  CONCLUSIONS
  N-glycosylation at Asn(628) is essential not only for NEP activities, but also for surface expression.
  
  
  CONCLUSIONS
  Quality control system does not allow dysfunctional ecto-type proteases to express on plasma membrane.
authors: Department of Pediatric Hematology and Oncology Research, National Research Institute for Child Health and Development, Setagaya-ku, Tokyo, Japan.
authors: Ban
authors: B
authors: Sato
authors: Yohko U
authors: YU
authors: Katagiri
authors: Kazutoshi
authors: K
authors: Iijima
authors: Hiroyuki
authors: H
authors: Yamada
authors: Satsuki
authors: S
authors: Ito
authors: Nana
authors: N
authors: Kawasaki
authors: Hajime
authors: H
authors: Okita
authors: Junichiro
authors: J
authors: Fujimoto
authors: Nobutaka
authors: N
authors: Kiyokawa
mesh_terms: D006026:Glycoside Hydrolases / Q000494:pharmacology; D006031:Glycosylation; D057809:HEK293 Cells; D006801:Humans; D021962:Membrane Microdomains / Q000737:chemistry; D015260:Neprilysin / Q000032:analysis / Q000737:chemistry* / Q000502:physiology*
chemical_list: D006026:Glycoside Hydrolases; D015260:Neprilysin