RGD Reference Report - O-glycosylation of mucin-like domain retains the neutral ceramidase on the plasma membranes as a type II integral membrane protein. - Rat Genome Database

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O-glycosylation of mucin-like domain retains the neutral ceramidase on the plasma membranes as a type II integral membrane protein.

Authors: Tani, Motohiro  Iida, Hiroshi  Ito, Makoto 
Citation: Tani M, etal., J Biol Chem. 2003 Mar 21;278(12):10523-30. doi: 10.1074/jbc.M207932200. Epub 2002 Dec 23.
RGD ID: 13838791
Pubmed: PMID:12499379   (View Abstract at PubMed)
DOI: DOI:10.1074/jbc.M207932200   (Journal Full-text)

Ceramidase is a key enzyme involved in regulating cellular levels of ceramide, sphingosine, and possibly sphigosine 1-phosphate and thus could modulate sphingolipid signaling. Here we report that O-glycosylation of the mucin-like domain of neutral ceramidases was required for localization to the surface of plasma membranes. The deduced amino acid sequences of the mammalian enzymes contain a serine-threonine-rich domain (mucin box), which follows the signal/anchor sequence, whereas those of bacterial and invertebrate enzymes completely lack a mucin box, suggesting that the specific domain has been acquired during evolution. In HEK293 cells overexpressing ceramidase, the enzyme was not only secreted into the medium after cleavage of the NH(2)-terminal signal/anchor sequence but also localized at the plasma membrane as a type II integral membrane protein. Lectin blot analysis using peanut agglutinin revealed that the mucin box of the enzyme is highly glycosylated with O-glycans. Interestingly, a mutant lacking the mucin box or possible O-glycosylation sites in the mucin box was secreted into the medium but not localized at the surface of the cells. Furthermore, a mucin box-fused chimera green fluorescent protein (GFP), but not GFP itself, with the signal/anchor sequence was distributed on the surface of the cells. These results suggest that O-glycosylation of the mucin box retains proteins on the plasma membranes. We also found that the 112-kDa membrane-bound enzyme from mouse kidney is O-glycosylated, whereas the 94-kDa soluble enzyme from liver is not. These results clearly indicate that post-translational modification of the enzyme with O-glycans is tissue-specific and helps the enzyme to localize at the surface of plasma membranes as a type II membrane protein.



Gene Ontology Annotations    Click to see Annotation Detail View

Cellular Component

  
Object SymbolSpeciesTermQualifierEvidenceWithNotesSourceOriginal Reference(s)
Asah2Ratextracellular space located_inIDA PMID:12499379UniProt 
Asah2Ratplasma membrane located_inIDA PMID:12499379UniProt 

Objects Annotated

Genes (Rattus norvegicus)
Asah2  (N-acylsphingosine amidohydrolase 2)


Additional Information