inositol 1,4,5-trisphosphate receptor type 1; IP3 receptor-1; type 1 inositol 1,4,5-trisphosphate receptor; type 1 insP3 receptor; IP3 receptor isoform 1; insP3R1; IP3R (ITPR1 INSP3R1)

Function

• intracellular channel that mediates Ca+2 release from the endoplasmic reticulum following stimulation by inositol 1,4,5-trisphosphate
• phosphorylated by cAMP kinase
• phosphorylation prevents the ligand-induced opening of the Ca+2 channels (putative)
• Ca+2 appears to inhibit ligand binding to the receptor, probably by interacting with a distinct Ca+2-binding protein which then inhibits the receptor
• phosphorylated on Tyr
• interacts with TRPC4
• interacts with RYR1, RYR2, ITPR1, SHANK1 & SHANK3
• interacts with TXNDC4 (pH-, redox- & Ca+2-dependent) inhibiting the Ca+2 channel activity; interaction inversely correlates with Ca+2 concentration
• part of cGMP kinase signaling complex at least composed of ACTA2/alpha-actin, CNN1/calponin H1, PLN/phospholamban, PRKG1 & ITPR1
• interacts with AHCYL1 (putative)
• interacts with MRVI1

Structure

• homotetramer
• the PPXXF motif binds HOM1, HOM2 & HOM3
• contains a Ca+2 channel in its C-terminal extremity
• large N-terminal cytoplasmic region has the ligand- binding site in the N-terminus & modulatory sites in the middle portion immediately upstream of the channel region
• belongs to the insP3 receptor family
• contains 5 MIR domains

Compartment

endoplasmic reticulum membrane

Alternative splicing

named isoforms=8

Expression

widely expressed

Pathology

• defects in ITPR1 are the cause of spinocerebellar ataxia type 15

More general terms

• transmembrane 6 protein
• inositol triphosphate [IP3] receptor P400 (ITPR, IP3-R)
• phosphoprotein

Additional terms

• inositol-1,4,5-triphosphate (IP3)

Database

• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:3708
• OMIM: https://mirror.omim.org/entry/147265
• OMIM: https://mirror.omim.org/entry/606658
• UniProt: http://www.uniprot.org/uniprot/Q14643.html