EC - Triphosphate—protein phosphotransferase

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IntEnz Enzyme Nomenclature


Accepted name:
triphosphate—protein phosphotransferase
Other names:
diphosphate:microsomal-membrane-protein O-phosphotransferase [incorrect]
pyrophosphate:protein phosphotransferase [incorrect]
pyrophosphate-protein phosphotransferase [incorrect]
DiPPT [incorrect]
diphosphate—protein phosphotransferase [incorrect]
diphosphate:[microsomal-membrane-protein] O-phosphotransferase [incorrect]
Systematic name:
triphosphate:[microsomal-membrane-protein] phosphotransferase



This enzyme was originally thought to use diphosphate as substrate [1] but this has since been disproved [2]. The activity is observed as the second part of a biphasic reaction after depletion of ATP. Tripolyphosphate is a contaminant of [γ-32P]ATP.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
Gene Ontology: GO:0047321
CAS Registry Number: 74092-32-3


  1. Lam, K.S. and Kasper, C.B.
    Pyrophosphate:protein phosphotransferase: a membrane-bound enzyme of endoplasmic reticulum.
    Proc. Natl. Acad. Sci. USA 77: 1927-1931 (1980). [PMID: 6246514]
  2. Tsutsui, K.
    Tripolyphosphate is an alternative phosphodonor of the selective protein phosphorylation of liver microsomal membrane.
    J. Biol. Chem. 261: 2645-2653 (1986). [PMID: 3949741]

[EC created 1983 as EC, transferred 2005 to EC]