ectonucleotide pyrophosphatase/phosphodiesterase family member 7; E-NPP 7; NPP-7; alkaline sphingomyelin phosphodiesterase; intestinal alkaline sphingomyelinase; alk-smase (ENPP7)

Function

• converts sphingomyelin to ceramide
• also has phospholipase C activity toward palmitoyl lyso-phosphocholine
• does not appear to have nucleotide pyrophosphatase activity

Inhibition:

• dose dependent inhibition by ATP, imidazole, orthovanadate & Zn+2
• not inhibited by ADP, AMP & EDTA

Structure

• N-glycosylation required for activity & transport to the plasma membrane
• belongs to the nucleotide pyrophosphatase/phosphodiesterase family

Compartment

• membrane; single-pass type 1 membrane protein (putative)
• localized at the surface of the microvillar membrane in small intestine enterocytes, & in endosome-like structures situated beneath the microvillar membrane, & in Golgi complex

Expression

• expressed in colon (at protein level)
• expressed in the duodenum, jejunum & liver & at low levels in the ileum
• expression is very low in esophagus, stomach

Pathology

• decreased levels of ENPP7 may be associated with colorectal carcicinoma

More general terms

• phosphoprotein phosphatase
• sphingomyelinase, sphinogomyelin phosphodiesterase
• glycoprotein

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=339221
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:339221
• UniProt: http://www.uniprot.org/uniprot/Q6UWV6.html