Jaw1 accelerates the reaction speed of the Ca(2+) signals via ITPRs upon GPCR stimulation.

Jaw1/LRMP/IRAG2 enhances Ca(2+) release via interaction with inositol 1,4,5-trisphosphate receptors (ITPRs), Ca(2+) channels on the endoplasmic reticulum, upon G protein-coupled receptor stimulation. While our previous works demonstrated the increases in the maximum amplitude and retention time of the Ca(2+) curve with heterogeneous effects on each ITPR subtype: ITPR1, ITPR2, and ITPR3, the effects on the reaction speed remain unclear. In this study, we unveiled the additional roles of Jaw1 in accelerating the signal onset time and rise time to the first peak top, especially in the cells expressing ITPR1. These findings shed more light on the relationship between the expression pattern of Jaw1 and ITPRs, and the heterogeneous pattern of the Ca(2+) dynamics, offering insights into their physiological implications.