Missense mutations in inositol 1,4,5-trisphosphate receptor type 3 result in leaky Ca channels and activation of store-operated Ca entry.

Mutations in all subtypes of the inositol 1,4,5-trisphosphate receptor Ca release channel are associated with human diseases. In this report, we investigated the functionality of three neuropathy-associated missense mutations in IPR3 (V615M, T1424M, and R2524C). The mutants only exhibited function when highly over-expressed compared to endogenous hIPR3.

Disrupted Ca homeostasis and immunodeficiency in patients with functional IP receptor subtype 3 defects.

Calcium signaling is essential for lymphocyte activation, with genetic disruptions of store-operated calcium (Ca) entry resulting in severe immunodeficiency. The inositol 1,4,5-trisphosphate receptor (IPR), a homo- or heterotetramer of the IPR1-3 isoforms, amplifies lymphocyte signaling by releasing Ca from endoplasmic reticulum stores following antigen stimulation. Although knockout of all IPR isoforms in mice causes immunodeficiency, the seeming redundancy of the isoforms is thought to explain the absence of variants in human immunodeficiency.

CREB regulates the expression of type 1 inositol 1,4,5-trisphosphate receptors.

Inositol 1,4,5-trisphosphate (IP3) receptors (IP3Rs) play a central role in regulating intracellular Ca2+ signals in response to a variety of internal and external cues. Dysregulation of IP3R signaling is the underlying cause for numerous pathological conditions. It is well established that the activities of IP3Rs are governed by several post-translational modifications, including phosphorylation by protein kinase A (PKA).