grk7a notes (DANRE, Q49HM9)
2026-09-28 session log
- Deep research FAILED for this gene (Edison: 402 Payment Required; OpenAI key invalid).
Not retried. Literature research done by hand via Europe PMC REST searches
(grk7a OR grk7b OR "GRK7-1" OR "GRK7-2", GRK7 AND (evolution OR phylogen*),
grk7b, GRK7 AND zebrafish AND (circadian OR UV cone OR paralog)), and by resolving
the DOIs cited in genes/DANRE/grk7b/grk7b-deep-research-falcon.md.
- Newly cached PMIDs: 34462505, 33579376, 33385424, 29321241, 19720650, 33598728,
40251282, 39925416, 18803695, 40869203, 22442725, 37190066, 39531499, 26246494, 34550876.
- GOA-cited PMIDs 16039565, 16787417, 21299656 are abstract-only in the cache;
30372740 and 36273582 are full text.
Naming (map every name before using it as evidence)
| Name in literature |
ZFIN gene |
Evidence |
| GRK7-1, zGRK7-1, Grk7a |
grk7a |
UniProt Q49HM9 synonym grk7-1; EMBL AB212995 (Wada 2006) on Q49HM9 |
| GRK7-2, zGRK7-2, Grk7b |
grk7b |
UniProt Q1XHL7 synonym grk7-2; EMBL AB212996 (Wada 2006) on Q1XHL7 |
| GRK7a (Rinner 2005) |
grk7a |
EMBL AY900004 (Rinner 2005) is on Q49HM9; the pineal paper uses AY900004 as its GRK7a probe PMID:33579376 |
| GRK1A / Grk1a |
grk1a (rod kinase) |
not this pair |
| GRK1B / Grk1b |
grk1b (cone kinase) |
not this pair |
Caution: several antibodies ("anti-Grk7", anti-carp GRK7, anti-pGRK7) recognise both
Grk7 paralogs, so "Grk7" immunoreactivity is not paralog-resolved unless a knockout or
knockdown control is used.
Key facts with provenance
Molecular function
- Recombinant GRK7-1 (grk7a) phosphorylates light-activated rhodopsin with very high Vmax:
PMID:16787417
- GRK7-2 (grk7b) is much slower (secondary citation of Wada 2006 by the same group):
PMID:33579376
- UniProt: KM=4.4 uM for rhodopsin, Vmax 773 nmol/min/mg (grk7a-uniprot.txt, from PMID:16787417).
- Both copies keep the PKA site (grk7a KKRRRS33; grk7b KKRRCS33) and a C-terminal CAAX
geranylgeranylation motif (grk7a ...CTLL, grk7b ...CTLL); sequence inspection of the two
UniProt records.
- The pair is 73% identical:
PMID:18803695
Regulation by cAMP/PKA (grk7a-specific data; grk7b untested)
Expression / localization
- Cone outer segments (GRK7-1): PMID:16787417
- All cones vs UV cones only: PMID:33598728
- Adult scRNA-seq partition: PMID:34462505
- Larval Grk7 protein is essentially all Grk7a: anti-Grk7 recognises both paralogs
PMID:30372740
but PMID:30372740
- Pineal: GRK1b, GRK7a and GRK7b mRNAs all detected in adult pineal
PMID:33579376
- Both transcripts oscillate with the same circadian phase:
PMID:34550876
- Recoverin 2b co-localises with Grk1b, Grk7a and Grk7b in double cones (abstract only, PMID:33385424) — note this is at odds with a strictly UV-cone-restricted grk7b.
Loss of function (grk7a)
Evolution
- PANTHER v19: TGD_tree, duplication on Neopterygii|Teleostei, 1 shared gar co-ortholog,
2 medaka co-orthologs (projects/DANRE_DUPLICATION/panther_tgd_pairs.tsv); grk7a is the
least-diverged ortholog (LDO) of human GRK7.
- PMID:34462505
- PMID:19720650
- Tetrapod/jawed-vertebrate GRK7 is single copy after 2R:
PMID:29321241
Annotation decisions (summary)
- MF rhodopsin kinase activity (IBA/IDA/IEA): ACCEPT, core.
- MF photoreceptor activity (IMP, Rinner 2005): REMOVE — a knockdown phenotype cannot
establish a photon-absorbing activity; grk7a is the kinase that inactivates the
photoreceptor protein, and its catalytic activity is already captured by GO:0050254 (IDA).
- BP photoresponse recovery (IMP x2): ACCEPT, core.
- BP phototransduction, visible light (IMP): ACCEPT (shut-off is part of the cascade).
- BP visual perception (IMP, PMID:21299656): KEEP_AS_NON_CORE.
- Broad kinase IEAs: MODIFY to GO:0050254 (consistent with grk7b review).
- NEW: CC cone photoreceptor outer segment (GO:0120199) from PMID:16787417 IHC.