Phospholipase C (PLC)
Phospholipase C (PLC) [EC 18.104.22.168] hydrolyzes phosphatidylinositol
4,5-bisphosphate to inositol 1,4,5-trisphosphate and diacylglycerol.
It has an absolute requirement for calcium and is activated by guanine
nucleotide binding proteins (PLC-_), or by receptor tyrosine kinases
(PLC-_), or by transglutaminase II (PLC-_). All three vertebrate
isoforms of PLC have a plekstrin homolog domain, followed by four
EF-hands, a triosephosphate isomerase-like _- barrel catalytic domain,
and a C2 domain . Although calcium is absolutely required for
activity, it is bound to the catalytic domain. None of the four
EF-hands have canonical calcium binding loops nor is Ca2+ bound in the
crystal structure .