at id y lin os it ol ▁signal ing ▁path way ▁The ▁de ▁nov o ▁b ios yn thesis ▁of ▁in os it ol ▁from ▁gl uc ose ▁ 6 - ph osph ate ▁ ▁I MP ase ▁in ▁the ▁ph osph at id y lin os it ol ▁signal ing ▁path way ▁ ▁In ▁this ▁path way , ▁G - cou ple d ▁protein ▁re cept ors ▁and ▁ty ros ine ▁kin ase ▁re cept ors ▁are ▁activ ated , ▁resulting ▁in ▁the ▁activation ▁of ▁ph osph ol ip ase ▁C ▁( PL C ). ▁P LC ▁hydro ly zes ▁ph osph at id y lin os it ol ▁bi ph osph ate ▁( PI P 2 ), ▁resulting ▁in ▁a ▁memb rane ▁associated ▁product , ▁dia cy l gly cer ol ▁( DA G ), ▁and ▁a ▁water - sol ub le ▁product , ▁ ▁in os it ol ▁tri ph osph ate ▁( IP 3 ). ▁D AG ▁acts ▁as ▁a ▁second ▁mess enger , ▁activ ating ▁several ▁protein ▁kin ases ▁and ▁produces ▁extended ▁down stream ▁signal ing . ▁IP 3 ▁is ▁also ▁a ▁second ▁mess enger ▁which ▁activ ates ▁re cept ors ▁on ▁the ▁end op las mic ▁ret icul um ▁to ▁release ▁calci um ▁ion ▁stores ▁into ▁the ▁cy top las m , ▁creating ▁a ▁complex ▁signal ing ▁system ▁that ▁can ▁be ▁involved ▁in ▁mod ulating ▁fert il ization , ▁pro l ifer ation , ▁contra ction , ▁cell ▁met abol ism , ▁ves icle ▁and ▁fluid ▁secret