Quantal Ca²⁺ release mediated by very few IP₃ receptors that rapidly inactivate allows graded responses to IP₃.

ABSTRACT: Inositol 1,4,5-trisphosphate receptors (IP₃Rs) are intracellular Ca²⁺ channels that link extracellular stimuli to Ca²⁺ signals. Ca²⁺ release from intracellular stores is "quantal": low IP₃ concentrations rapidly release a fraction of the stores. Ca²⁺ release then slows or terminates without compromising responses to further IP₃ additions. The mechanisms are unresolved. Here, we synthesize a high-affinity partial agonist of IP₃Rs and use it to demonstrate that quantal responses do not require heterogenous Ca²⁺ stores. IP₃Rs respond incrementally to IP₃ and close after the initial response to low IP₃ concentrations. Comparing functional responses with IP_3</

SUBMITTER: Rossi AM 

PROVIDER: S-EPMC8578705 | biostudies-literature | 2021 Nov

REPOSITORIES: biostudies-literature