Gene Ontology annotation through association of InterPro records with GO terms
Manual transfer of experimentally-verified manual GO annotation data to orthologs by curator judgment of sequence similarity
Annotation inferences using phylogenetic trees
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
Combined Automated Annotation using Multiple IEA Methods
Knockdown of cone-specific kinase GRK7 in larval zebrafish leads to impaired cone response recovery and delayed dark adaptation.
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Morpholino knockdown of grk7a delays cone photoresponse recovery and reduces temporal contrast sensitivity; two grk7 orthologs were cloned.
"Photoresponse recovery in Grk7a-deficient larvae was delayed in electroretinographic measurements, and temporal contrast sensitivity was reduced, particularly under bright-light conditions."
GRK1 and GRK7: unique cellular distribution and widely different activities of opsin phosphorylation in the zebrafish rods and cones.
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GRK7-1 (grk7a) localizes to cone outer segments and has a rhodopsin-phosphorylation Vmax 32-fold higher than rod GRK1A.
"The recombinant GRKs phosphorylated light-activated rhodopsin, and the Vmax value of the major cone subtype, GRK7-1, was 32-fold higher than that of the rod kinase, GRK1A."
Cone arrestin confers cone vision of high temporal resolution in zebrafish larvae.
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Grk7a acts in initial cone response recovery, overlapping with arr3a.
"Arr3a activity partially overlapped with the function of the cone-specific kinase Grk7a involved in initial response recovery."
Grk1b and Grk7a Both Contribute to the Recovery of the Isolated Cone Photoresponse in Larval Zebrafish.
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grk7a knockout larvae have modestly slower cone photoresponse recovery; Grk1b contributes similarly.
"Since the difference between wildtype and each knockout fish is modest, it appears that either GRK is sufficient for adequate cone visual function."
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An antibody that detects both Grk7 paralogs finds no Grk7 in grk7a knockout larvae, so larval retinal Grk7 is Grk7a.
"Analysis of grk7a−/− larvae at 5 dpf show undetectable levels of Grk7 compared to wildtype (Fig. 2A, 2B)."
Grk7 but not Grk1 undergoes cAMP-dependent phosphorylation in zebrafish cone photoreceptors and mediates cone photoresponse recovery to elevated cAMP.
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Grk7a mediates the cAMP-induced delay in cone recovery and is phosphorylated via PKA.
"We also used a cone-specific dominant negative PKA transgenic zebrafish to show that PKA is part of the endogenous kinase pathway responsible for Grk7a phosphorylation in response to elevated cAMP."
Functional identification of an opsin kinase underlying inactivation of the pineal bistable opsin parapinopsin in zebrafish.
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GRK7a is the main kinase inactivating the parapinopsin photoproduct in pineal photoreceptor cells; GRK7b knockdown has little effect.
"We found that GRK7a knockdown slowed recovery of the response of parapinopsin photoreceptor cells, whereas GRK1b knockdown or GRK7b knockdown did not have a remarkable effect"
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GRK7a (GRK7-1) rhodopsin phosphorylation is more than 30-fold faster than that of GRK7b (GRK7-2).
"rhodopsin phosphorylation activity of GRK7a (GRK7–1) is more than 30-fold faster than those of GRK1a, GRK1b, and GRK7b (GRK7–2 [29])"
Light intensity-dependent arrestin switching for inactivation of a light-sensitive GPCR, bistable opsin.
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In pineal parapinopsin cells, GRK7b and GRK1b contribute to response termination in addition to GRK7a (multiple knockdowns).
"These observations suggest that GRK7b and also presumably GRK1b contribute to the response termination processes in addition to GRK7a in control fish."
Partitioning of gene expression among zebrafish photoreceptor subtypes.
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In adult photoreceptor scRNA-seq, grk7b is UV-cone-enriched while grk7a is enriched in the other cone types; the pair arose in the TGD.
"Additionally, we found multiple pairs of paralogous genes that were differentially enriched between UV cones (grk7b, cngb3.2, and guca1e) and other cone types (grk7a, cngb3.1, and guca1e.2)."
Biochemistry and physiology of zebrafish photoreceptors.
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grk7a is expressed in all cones, grk7b only in UV cones.
"grk1a is expressed exclusively in rods, grk1b and grk7a in all cones, and grk7b only in UV cones"
Phosphorylation of GRK7 by PKA in cone photoreceptor cells is regulated by light.
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The two zebrafish GRK7 paralogs are 73% identical.
"In comparison, the 2 zebrafish GRK7 proteins, zGRK7-1 and zGRK7-2 are only 73% identical at the amino acid level"
Evolution of the shut-off steps of vertebrate phototransduction.
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Jawed vertebrates kept a single GRK7 after 2R; GRK7s are geranylgeranylated.
"It is also clear that, following 2R WGD, jawed vertebrates retained two GRK1 isoforms but only a single GRK7, whereas agnathan vertebrates retained two GRK7 isoforms but only a single GRK1."
Recoverin depletion accelerates cone photoresponse recovery.
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Grk7a knockdown prolongs UV-cone (SWS1) response recovery, so grk7a acts in UV cones too.
"indicating Grk7a is a general cone opsin kinase"
Circadian regulation of vertebrate cone photoreceptor function.
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grk7a and grk7b transcripts oscillate with a similar circadian phase.
"Although many ohnologs (paralogs generated in a whole-genome duplication event), such as grk7a and grk7b, share a similar circadian phase or oscillatory amplitude"
UniProtKB entry Q49HM9 for Danio rerio grk7a