| 2000 |
IRAG forms a trimeric signaling complex with cGKIβ and IP3 receptor type I (IP3R-I) at endoplasmic reticulum membranes in smooth muscle. In microsomal smooth muscle membranes, cGKIβ phosphorylated IRAG and IP3R. Co-expression of IRAG and cGKIβ in COS-7 cells, in the presence of cGMP, inhibited bradykinin-stimulated calcium release, identifying IRAG as an essential NO/cGKI-dependent regulator of IP3-induced calcium release. |
Co-immunoprecipitation with antibodies against cGKI, IP3R, and IRAG; heterologous expression in COS-7 cells; calcium release assays; mass spectrometry protein identification |
Nature |
High |
10724174
|
| 2001 |
The N-terminal leucine zipper (amino acids 1–53) of cGKIβ (but not cGKIα or cGKII) interacts with amino acids 152–184 of IRAG via electrostatic interaction. cGKIβ does not directly interact with IP3R-I but co-precipitates IP3R-I through IRAG. cGKIβ phosphorylates up to four serines in IRAG; phosphorylation specifically of Ser696 is necessary and sufficient to decrease IP3-dependent calcium release. |
Yeast two-hybrid; co-precipitation of expressed proteins; site-directed mutagenesis (four Ser→Ala mutants); calcium release assays in transfected cells |
The Journal of biological chemistry |
High |
11309393
|
| 2004 |
Targeted deletion of exon 12 of IRAG (encoding the N-terminus of the coiled-coil domain) disrupts the IRAG–IP3R-I interaction in vivo, abolishing cGMP-dependent relaxation of carbachol- and phenylephrine-contracted smooth muscle from colon and aorta and preventing cGMP-mediated decrease in norepinephrine-induced [Ca2+]i in aortic smooth muscle cells. cGMP-induced relaxation of K+-contracted smooth muscle was unaffected, indicating IRAG is specifically required for hormone receptor–triggered cGMP relaxation. |
Genetic knockout (exon 12 deletion); smooth muscle contraction/relaxation assays; intracellular calcium measurements (Fura-2); gastrointestinal motility assessment |
The EMBO journal |
High |
15483626
|
| 2004 |
Endogenous IRAG in human colonic smooth muscle cells is required for NO/cGKI-dependent inhibition of IP3-dependent Ca2+ release. Antisense knockdown of IRAG abolished sodium nitroprusside- and 8-pCPT-cGMP-mediated inhibition of bradykinin-induced calcium transients. |
Antisense oligonucleotide knockdown of IRAG in cultured human colonic smooth muscle cells; calcium imaging; RT-PCR |
The Journal of biological chemistry |
Medium |
14729908
|
| 2004 |
IRAG co-localizes with cGKI in smooth muscle of aorta and colon. Upon co-expression in COS-7 cells, IRAG recruits cGKIβ (but not cGKIα) to the endoplasmic reticulum, demonstrating isoform-specific targeting by IRAG. |
Immunofluorescence/immunohistochemistry in murine tissues; heterologous co-expression in COS-7 cells with confocal microscopy |
FEBS letters |
Medium |
15388327
|
| 2005 |
Acidic residues in the N-terminal leucine zipper dimerization domain of PKGIβ (D26 and E31) mediate binding to both TFII-I and IRAG via electrostatic interaction with basic residues in alpha-helical regions of IRAG. Mutation D26K/E31R in PKGIβ completely abrogated binding to IRAG without disrupting PKG dimerization. |
Site-directed mutagenesis; in vitro binding assays; co-immunoprecipitation in intact cells |
The Journal of biological chemistry |
High |
16166082
|
| 2006 |
IRAG is abundantly expressed in platelets and assembles in a macrocomplex with cGKIβ and IP3R-I. PKGIβ phosphorylates IRAG at Ser664 and Ser677 in intact platelets. Targeted disruption of the IRAG–IP3R-I interaction (IRAGΔ12/Δ12 mice) abolishes NO/cGMP-dependent inhibition of fibrinogen-receptor activation, platelet aggregation, and intracellular calcium transients, and prevents NO-mediated inhibition of arterial thrombosis in vivo. |
IRAG exon 12 deletion mouse model; intravital microscopy; platelet aggregation assays; calcium imaging; phosphorylation site mapping by mass spectrometry |
Blood |
High |
16990611
|
| 2008 |
IRAG anchors PKGIβ to the endoplasmic reticulum, preventing cGMP-induced nuclear translocation of PKGIβ and thereby reducing cGMP/PKGIβ-mediated transcriptional activation of a CRE-reporter gene. This effect required the PKGIβ–IRAG binding interface and was specific to PKGIβ (PKGIα was unaffected). A phosphorylation-deficient IRAG mutant still suppressed PKGIβ transcriptional activity, indicating the mechanism is independent of IRAG phosphorylation or changes in intracellular calcium. |
Co-expression of wild-type and binding-incompetent/phosphorylation-deficient IRAG mutants in baby hamster kidney cells; CRE-reporter gene assay; subcellular localization by imaging |
Cellular signalling |
Medium |
18450420
|
| 2010 |
Global IRAG knockout (exon 3 deletion) prevents stable interaction of IP3R-I with cGKIβ (shown by cGMP affinity chromatography) and abolishes NO-, ANP-, and cGMP-dependent relaxation of hormone-contracted aortic and colonic smooth muscle. cGKIβ/α subcellular localization in VSMCs was unchanged by IRAG loss. IRAG-deficient VSMCs failed to suppress hormone-induced Ca2+ increases in response to cGMP. Selective cGKIβ re-expression in smooth muscle from cGKIβ-transgenic mice did not rescue relaxation, confirming IRAG is obligate downstream of cGKIβ. IRAG-deficient mice showed resistance to LPS-induced blood pressure reduction. |
Targeted exon 3 deletion mouse model; cGMP affinity chromatography; confocal microscopy; Fura-2 calcium imaging; smooth muscle relaxation assays; telemetric blood pressure measurement; transgenic rescue experiment |
Cardiovascular research |
High |
20080989
|
| 2011 |
IRAG-deficient murine platelets show enhanced aggregability to collagen, thrombin, and TxA2. NO/cGMP-dependent inhibition of ATP and 5-HT secretion from dense granules, P-selectin secretion from alpha granules, and GPIIb/IIIa-mediated adhesion to fibrinogen were all severely impaired in IRAG-deficient platelets, and bleeding time was reduced. |
IRAG knockout mouse model; platelet aggregation assays; granule secretion assays (ATP, 5-HT); flow cytometry (P-selectin); adhesion assays; bleeding time measurement |
Platelets |
High |
21244222
|
| 2011 |
C-terminally truncated IRAG variants lacking the cGKI phosphorylation site and IP3R-I interaction site act as dominant-negative modulators, counteracting cGMP-mediated inhibition of calcium transients and relaxation of human colonic smooth muscle cells. Four unique first-exon variants driven by individual promoters and extensive alternative splicing generate multiple truncated IRAG isoforms. |
Identification of splice variants by RT-PCR/sequencing; functional expression of truncated IRAG variants in colonic smooth muscle cells; calcium imaging; contractility assays |
American journal of physiology. Cell physiology |
Medium |
21865585
|
| 2021 |
IRAG, PKGIβ, and IP3Rs form a nanoscale signaling complex on the SR of vascular smooth muscle cells, identified by superresolution microscopy. PKG phosphorylation of IRAG inhibits IP3R-mediated Ca2+ release; IRAG knockdown diminished NO-mediated inhibition of TRPM4 channel activity and vasodilation. Thus, IRAG mediates NO/cGMP/PKG inhibition of IP3R-dependent TRPM4 activation to dilate cerebral arteries. |
IRAG knockdown in vascular SMCs; patch-clamp electrophysiology (TRPM4 currents); Ca2+ imaging; superresolution microscopy of IRAG/PKG/IP3R nanoscale complex; pharmacological inhibition of guanylyl cyclase and PKG |
Function (Oxford, England) |
High |
34734188
|
| 2020 |
IRAG1 knockout mice spontaneously develop right ventricular hypertrophy, elevated RV systolic pressure, RV dysfunction, and pulmonary hypertension under normoxic conditions. IRAG1 is expressed in PASMCs and is downregulated under hypoxia. Absence of IRAG1 reduces PKGIβ expression in lung and RV and dysregulates downstream PKGIβ candidates in the RV. |
Global IRAG1 KO mouse model; echocardiography; right heart catheterization; immunostaining; western blotting; PASMC isolation |
Cells |
Medium |
33066124
|
| 2021 |
Global IRAG1 KO mice develop gastrointestinal bleeding, iron-deficiency anemia, and anemia-associated splenomegaly. Loss of IRAG1 strongly decreases PKGIβ protein levels (but not mRNA) in colon, spleen, and stomach, indicating IRAG1 is required for PKGIβ protein stability. |
Global IRAG1 KO mouse model; western blotting; RT-PCR; histology; hematological analysis |
International journal of molecular sciences |
Medium |
34064290
|
| 1999 |
Mrvi1 (IRAG1 ortholog) encodes a protein with homology to Jaw1, a lymphoid-restricted type II membrane protein localizing to the endoplasmic reticulum. Within hematopoietic cells, Mrvi1 expression is restricted to megakaryocytes and some myeloid leukemias, and is downregulated during monocytic differentiation. |
Retroviral insertional mutagenesis screen; sequence homology analysis; Northern blot expression analysis |
Oncogene |
Low |
10321731
|
| 2025 |
TurboID-based proximity labeling identified >700 candidate MRVI1-interacting proteins in mammalian cells, including ER-localized factors and intracellular trafficking components. Co-expression of NPM-ALK oncogenic kinase selectively enhanced MRVI1 association with signaling-related proteins and reduced association with anti-apoptotic regulators (DDB1, PHB2, NOTCH2), suggesting MRVI1 participates in apoptosis-related networks disrupted during oncogenic transformation. |
TurboID proximity labeling; quantitative proteomics; co-expression of NPM-ALK |
Journal of biochemistry |
Low |
41078212
|
| 2026 |
Stable overexpression of MRVI1 in HCT116 colorectal cancer cells markedly reduces cell proliferation without increasing cell death (cytostatic effect), providing direct evidence that MRVI1 suppresses colorectal cancer cell growth when overexpressed, consistent with a p53-associated tumor suppressor role. |
Stable overexpression of V5-TurboID-MRVI1 fusion protein; cell proliferation assays; trypan blue viability staining |
Biological & pharmaceutical bulletin |
Low |
41905951
|