| 2002 |
MYRIP (MyRIP) was identified as a novel protein that binds to myosin VIIa and to Rab27A in a GTP-dependent manner. In retinal pigment epithelium cells, MyRIP, myosin VIIa, and Rab27A co-associate with melanosomes, and overexpression of MyRIP interferes with myosin VIIa tail localization in transfected PC12 cells, indicating MyRIP bridges melanosomes to the actin cytoskeleton via this complex. |
Co-immunoprecipitation, GTP-dependent binding assay, overexpression in PC12 cells, immunolocalization in RPE cells |
EMBO reports |
Medium |
11964381
|
| 2002 |
Slac2-c/MYRIP was identified as a linker protein with an N-terminal Slp homology domain (SHD) that binds GTP-bound Rab27A/B both in vitro and in intact cells, a middle region that binds myosin Va and myosin VIIa, and a C-terminal actin-binding domain. The actin-binding domain colocalizes with actin filaments at the cell periphery when expressed in PC12 cells and melanoma cells. |
In vitro binding assays, GST pulldown, co-immunoprecipitation, immunofluorescence in transfected cells |
The Journal of biological chemistry |
High |
12221080
|
| 2003 |
Slac2c/MyRIP is associated with insulin-containing secretory granules of pancreatic beta-cells. siRNA knockdown of Slac2c/MyRIP severely impairs hormone release in response to secretagogues. Overexpression of the actin-binding domain (but not the myosin Va-binding domain) of Slac2c/MyRIP potently inhibits exocytosis, and point mutations abolishing actin binding prevent this inhibition, demonstrating that the actin-binding domain is the key functional element for regulating insulin exocytosis. |
siRNA knockdown, overexpression of domain mutants, insulin secretion assay, point mutagenesis |
Molecular biology of the cell |
High |
14517322
|
| 2005 |
In vitro binding experiments showed that myosin VIIa has greater affinity for Slac2-c/MYRIP than myosin Va, and the myosin VIIa-binding domain is distinct from the myosin Va-binding domain. In melanocytes, ectopic expression of Slac2-c recruits co-expressed myosin VIIa to melanosomes via Rab27A interaction, and the Slac2-c/myosin VIIa complex rescues normal melanosome distribution in Slac2-a-depleted melanocytes, establishing Slac2-c as a functional myosin VIIa receptor. |
In vitro pulldown, co-immunoprecipitation, siRNA knockdown of Slac2-a, ectopic expression with fluorescent tags in melanocytes, melanosome distribution assay |
The Journal of biological chemistry |
High |
15927964
|
| 2007 |
MYRIP was identified as a member of the AKAP (A-kinase anchoring protein) family. Mouse MyRIP targets the type II PKA holoenzyme to a specific perinuclear region of insulin-secreting cells via an atypical mechanism. MyRIP also interacts with the Sec6 and Sec8 components of the exocyst complex, linking PKA to the exocytosis machinery. |
Yeast two-hybrid screen (zebrafish ortholog Ze-AKAP2), biochemical pulldown, co-immunoprecipitation, immunofluorescence in insulin-secreting cells |
The Journal of biological chemistry |
Medium |
17827149
|
| 2007 |
All three proteins Rab27a, Myrip, and Myosin VIIa co-immunoprecipitate in heterologous cultured cells and co-localize at the peripheral membrane of RPE melanosomes. Live-cell imaging of RPE primary cultures shows that loss of any one of the three components (ashen/Rab27a-deficient, shaker-1/MyoVIIa mutant, or Myrip-knockdown cells) leads to increased melanosome motility with more frequent fast movements and inversion of directionality, similar to cytochalasin D treatment, indicating the Rab27a-Myrip-MyoVIIa complex tethers melanosomes to actin filaments for peripheral directionality. |
Co-immunoprecipitation, immunofluorescence and immunoelectron microscopy, live-cell imaging of RPE primary cultures, adenoviral knockdown, mutant mouse RPE cells, cytochalasin D treatment |
Traffic (Copenhagen, Denmark) |
High |
17451552
|
| 2007 |
In RPE cells, MYRIP is linked to melanosomes via RAB27A as shown by mutant mouse analysis, but recruitment of MYRIP to the apical RPE region is independent of melanosomes and RAB27A. RAB27A provides an essential link to melanosomes, and RAB27A together with MYRIP also associates with motile small vesicles of unknown origin. |
RPE primary cultures, live-cell imaging, mutant mouse retina analysis, cell fractionation |
Cell motility and the cytoskeleton |
Medium |
17352418
|
| 2009 |
Rab27a and MyRIP are present on mature Weibel-Palade bodies (WPBs) in endothelial cells and anchor WPBs to peripheral actin. siRNA depletion of either Rab27a or MyRIP causes loss of peripheral WPB localization, increases both basal and stimulated secretion, and results in VWF that is less multimerized with shorter platelet-binding strings under flow. |
siRNA depletion in primary endothelial cells, immunofluorescence localization, VWF secretion assay, VWF multimerization analysis, flow-based string assay |
Blood |
High |
19270261
|
| 2009 |
Myrip recruits and activates myosin Va on skin melanosomes with similar efficiency to melanophilin. Mutagenesis demonstrated that a conserved Myrip-Melanophilin amphipathic helix (MMAH) is essential for myosin Va interaction, while Myrip-specific inserts (not the MMAH) are essential for myosin VIIa activation, showing that Myrip activates MyoVa and MyoVIIa via non-overlapping distinct domains. |
Melanocyte and RPE cell melanosome transport assays, domain mutagenesis, fluorescence microscopy |
Pigment cell & melanoma research |
Medium |
19317802
|
| 2009 |
After beta-adrenergic stimulation of rat parotid acinar cells, Slac2-c/MYRIP is rapidly recruited from secretory granules to the apical plasma membrane fraction and subsequently translocated to the cytosol. In the cytosolic fraction, Slac2-c is Ca2+-dependently proteolyzed, likely via PEST sequences, indicating dynamic redistribution and degradation after exocytosis. |
Subcellular fractionation, isoproterenol stimulation, Ca2+ treatment, immunoblotting |
Archives of oral biology |
Medium |
19185850
|
| 2011 |
Myosin Va forms a tripartite complex with Rab27a and MyRIP on Weibel-Palade bodies in endothelial cells. Depletion of or dominant-negative interference with myosin Va increases the ratio of perinuclear to peripheral WPBs and elevates secretion of less-oligomeric VWF from histamine-stimulated cells, indicating the Rab27a/MyRIP/myosin Va complex links WPBs to peripheral actin for maturation. |
Co-immunoprecipitation, siRNA depletion, dominant-negative overexpression, immunofluorescence, VWF oligomerization analysis |
Traffic (Copenhagen, Denmark) |
Medium |
21740491
|
| 2012 |
MYRIP acts as a negative regulator of WPB exocytosis and Slp4-a acts as a positive regulator; both effects are mediated by Rab27A. siRNA knockdown and overexpression experiments show that the balance of Rab27A fractional occupancy by Slp4-a vs. MyRIP on WPBs determines the probability of WPB exocytosis. |
siRNA knockdown, EGFP-tagged overexpression, live-cell imaging, exocytosis quantification in endothelial cells |
Blood |
Medium |
22898601
|
| 2012 |
In human enterochromaffin cells, Myrip (1) inhibits fast directed secretory granule movement (facilitating dissociation from microtubules), (2) enhances granule motion toward and attachment to the plasma membrane, and (3) increases granule immobilization time at the plasma membrane. Effects (1) and (2) depend on myosin Va recruitment, while effect (3) is myosin Va-independent but requires the C-terminal domain of Myrip, likely involving actin/exocyst interactions. |
TIRF microscopy, single-particle tracking, photoconversion assay, mathematical modeling, domain deletion/mutation analysis |
The Journal of neuroscience |
High |
22396429
|
| 2012 |
In glucose-stimulated pancreatic beta cells, MyRIP does not interact with the brain isoform of myosin Va (BR-MyoVa) under basal conditions. However, elevation of cAMP by incretin hormones leads to MyRIP phosphorylation, its interaction with BR-MyoVa, and phosphorylation of the secretory granule-associated protein rabphilin-3A (Rph-3A) on Ser-234. siRNA knockdown of MyRIP reduces cAMP-mediated Rph-3A phosphorylation and hormone secretion, and phosphomutant/phosphomimic Rph-3A significantly alters hormone release when PKA is activated. |
In vitro pulldown, co-immunoprecipitation, siRNA knockdown, phosphorylation assay, phosphomutant expression, insulin secretion assay |
Molecular biology of the cell |
Medium |
22993210
|
| 2015 |
In endothelial cells, MyRIP restricts WPB movement through its actin-binding domain rather than through its myosin Va-binding domain. For Ca2+-driven exocytosis, both MyoVa- and actin-binding are required, but actin-binding plays the dominant role. These conclusions were established using EGFP-MyRIP point mutants with disrupted MyoVa and/or actin binding and high-speed live-cell fluorescence microscopy. |
Point mutagenesis of MyRIP (disrupting MyoVa- and/or actin-binding), high-speed live-cell fluorescence microscopy, actin disruption/stabilization experiments, Ca2+-evoked exocytosis assay |
Journal of cell science |
High |
26675235
|
| 2017 |
Exophilin-8/MYRIP accumulates secretory granules in the cortical F-actin network not by direct interaction with myosin Va, but through indirect interaction with myosin VIIa via a previously unknown binding partner, RIM-BP2. RIM-BP2 also associates with exocytic machinery components Cav1.3, RIM, and Munc13-1. Ablation or knockdown of exophilin-8, RIM-BP2, or myosin VIIa markedly decreases both peripheral granule accumulation and exocytosis. In exophilin-8-null mouse pancreatic islets, polarized granule localization is lost and insulin secretion is impaired. |
Co-immunoprecipitation, knockdown/knockout mouse models, immunofluorescence, insulin secretion assay, interaction domain mapping |
eLife |
High |
28673385
|