Previous studies have indicated that ERp44 inhibits inositol 1,4,5-trisphosphate(IP3)-induced Ca2+release(IICR)via IP3R1,but the mechanism remains largely unexplored.Using extracellular ATP to induce intracellular cal...Previous studies have indicated that ERp44 inhibits inositol 1,4,5-trisphosphate(IP3)-induced Ca2+release(IICR)via IP3R1,but the mechanism remains largely unexplored.Using extracellular ATP to induce intracellular calcium transient as an IICR model,Ca2+image,pull down assay,and Western blotting experiments were carried out in the present study.We found that extracellular ATP induced calcium transient via IP3Rs(IICR)and the IICR were markedly decreased in ERp44 overexpressed Hela cells.The inhibitory effect of C160S/C212S but not C29S/T396A/ΔT(331–377)mutants of ERp44 on IICR were significantly decreased compared with ERp44.However,the binding capacity of ERp44 to L3V domain of IP3R1(1L3V)was enhanced by ERp44 C160S/C212S mutation.Taken together,these results suggest that the mutants of ERp44,C160/C212,can more tightly bind to IP3R1 but exhibit a weak inhibition of IP3R1 channel activity in Hela cells.展开更多
基金by grants from the National Basic Research Program of China(Grant Nos.2011CB8091004 and 2009CB918701)the National Natural Science Foundation of China(Grant No.81100539).
文摘Previous studies have indicated that ERp44 inhibits inositol 1,4,5-trisphosphate(IP3)-induced Ca2+release(IICR)via IP3R1,but the mechanism remains largely unexplored.Using extracellular ATP to induce intracellular calcium transient as an IICR model,Ca2+image,pull down assay,and Western blotting experiments were carried out in the present study.We found that extracellular ATP induced calcium transient via IP3Rs(IICR)and the IICR were markedly decreased in ERp44 overexpressed Hela cells.The inhibitory effect of C160S/C212S but not C29S/T396A/ΔT(331–377)mutants of ERp44 on IICR were significantly decreased compared with ERp44.However,the binding capacity of ERp44 to L3V domain of IP3R1(1L3V)was enhanced by ERp44 C160S/C212S mutation.Taken together,these results suggest that the mutants of ERp44,C160/C212,can more tightly bind to IP3R1 but exhibit a weak inhibition of IP3R1 channel activity in Hela cells.
