ITPR1 Antibody – Rabbit Polyclonal

This gene encodes an intracellular receptor for inositol 1,4,5-trisphosphate. Upon stimulation by inositol 1,4,5-trisphosphate, this receptor mediates calcium release from the endoplasmic reticulum. Mutations in this gene cause spinocerebellar ataxia type 15, a disease associated with an heterogeneous group of cerebellar disorders. Multiple transcript variants have been identified for this gene. [provided by RefSeq, Nov 2009]

Function: Intracellular channel that mediates calcium release from the endoplasmic reticulum following stimulation by inositol 1,4,5-trisphosphate. Plays a role in ER stress-induced apoptosis. Cytoplasmic calcium released from the ER triggers apoptosis by the activation of CaM kinase II, eventually leading to the activation of downstream apoptosis pathways

By similarity.

Subunit structure: Homotetramer. Interacts with TRPC4. The PPXXF motif binds HOM1, HOM2 and HOM3. Interacts with RYR1, RYR2, ITPR1, SHANK1 and SHANK3. Interacts with ERP44 in a pH-, redox state- and calcium-dependent manner which results in the inhibition the calcium channel activity. The strength of this interaction inversely correlates with calcium concentration. Part of cGMP kinase signaling complex at least composed of ACTA2/alpha-actin, CNN1/calponin H1, PLN/phospholamban, PRKG1 and ITPR1. Interacts with AHCYL1

By similarity. Interacts with MRVI1 and CABP1 (via N-terminus). Ref.7 Ref.8 Ref.9 Ref.11

Subcellular location: Endoplasmic reticulum membrane; Multi-pass membrane protein.

Tissue specificity: Widely expressed.

Domain: The receptor contains a calcium channel in its C-terminal extremity. Its large N-terminal cytoplasmic region has the ligand-binding site in the N-terminus and modulatory sites in the middle portion immediately upstream of the channel region.

Post-translational modification: Phosphorylated by cAMP kinase. Phosphorylation prevents the ligand-induced opening of the calcium channels

By similarity. Ref.2Phosphorylated on tyrosine residues. Ref.2Ubiquitination at multiple lysines targets ITPR1 for proteasomal degradation. Approximately 40% of the ITPR1-associated ubiquitin is monoubiquitin, and polyubiquitins are both 'Lys-48'- and 'Lys-63'-linked

By similarity.

Involvement in disease: Spinocerebellar ataxia 15 (SCA15) [MIM:606658]: Spinocerebellar ataxia is a clinically and genetically heterogeneous group of cerebellar disorders. Patients show progressive incoordination of gait and often poor coordination of hands, speech and eye movements, due to degeneration of the cerebellum with variable involvement of the brainstem and spinal cord. SCA15 is an autosomal dominant cerebellar ataxia (ADCA). It is very slow progressing form with a wide range of onset, ranging from childhood to adult. Most patients remain ambulatory.Note: The disease is caused by mutations affecting the gene represented in this entry. Ref.12 Ref.16Spinocerebellar ataxia 29 (SCA29) [MIM:117360]: An autosomal dominant, congenital spinocerebellar ataxia characterized by early motor delay, hypotonia and mild cognitive delay. Affected individuals develop a very slowly progressive or non-progressive gait and limb ataxia associated with cerebellar atrophy on brain imaging. Additional variable features include nystagmus, dysarthria, and tremor.Note: The disease is caused by mutations affecting the gene represented in this entry. Ref.17

Miscellaneous: Calcium appears to inhibit ligand binding to the receptor, most probably by interacting with a distinct calcium-binding protein which then inhibits the receptor.

Sequence similarities: Belongs to the InsP3 receptor family.Contains 5 MIR domains.

Caution: Alternative splice sites (AA 1053-1054) represent a non-canonical GA-AG donor-acceptor pair, but are well-supported by all available human transcripts, and by homologous transcripts in mouse, rat and cow.