Identity: Q9VVV2 is the canonical Swiss-Prot product of CG6836 (FBgn0036834). It is 328 aa, from the
single annotated transcript CG6836-RA. It is not a fragment, isoform or alternative gene model. Its
length matches vertebrate OST-alpha (326-340 aa), and it has seven predicted TM helices and four
predicted N-glycosylation sites at the N-terminus (positions 2, 15, 25, 42), all in the predicted
extracellular N-terminal domain 1-44.
Literature: there are no experimental papers on CG6836. The falcon deep research correctly flags that
dOSCP1 (CG13178) is a different protein. The only paper that names FBgn0036834 is Dawson et al. 2010
PMID:20538072. It also proposes that
the ancestral substrates were not bile acids PMID:20538072. Vertebrate
OST-alpha needs OST-beta for plasma-membrane delivery PMID:23506901.
Evolutionary placement: PTHR23423 is heterogeneous (OST-alpha, TMEM184, Hfl1, LAZ1). UniProt gives
only the family. The PANTHER 19.0 fruit-fly classification file has no row for Q9VVV2/FBgn0036834, and
the PANTHER geneinfo API returns no family for it. So CG6836 has no PANTHER subfamily and no PAINT
node, and there are no IBA rows. I built an MAFFT + NJ tree of 15 PTHR23423 members
(CG6836-bioinformatics/RESULTS.md). CG6836 is sister to vertebrate SLC51A (SF11/SF80) inside an
OST-alpha-like clade with worm osta-1/2/3. The fly paralogs Tmep (SF17) and CG5850 (SF10, the TMEM184C
group) fall outside that clade. Identity is low (15-21%) and the tree has no bootstrap, so the placement
is moderate. This is consistent with the Ensembl Compara ortholog call.
Family review interpro/panther/PTHR23423/PTHR23423-review.yaml: it uses CG6836 as the reference
protein and gives a single catch-all "subfamily" (OST-alpha/TMEM184/Hfl1). It does not disagree with
this placement. It simply makes no subfamily-level assignment, and its caution against transferring
bile-acid transport is the same as mine.
Annotation decisions (3 rows):
- plasma membrane (IEA, SubCell): ACCEPT. Ortholog inference, with the OST-beta caveat noted.
- membrane (IEA, ARBA): ACCEPT. Directly supported by the TM helices. The ARBA rule itself is not
used as evidence.
- membrane (ISS from mouse Slc51a Q8R000): ACCEPT. The donor is in the right lineage. The curators
transferred only the location, not bile-acid transport. That is treated as deliberate, so no MF or
BP is added.
No NEW annotations. Transporter MF and bile-acid/steroid transport BP are not asserted, because the
substrate and partner are unknown and the vertebrate activity requires OST-beta.
Relative for next review: human SLC51A (Q86UW1), the experimentally characterized OST-alpha. It is
an ortholog-lineage relative by tree and Ensembl Compara, not by a shared PANTHER subfamily, because
CG6836 has no subfamily assigned. There is no review in the repo. The module
modules/enterohepatic_bile_salt_cycling.yaml covers SLC51A in vertebrates. CG6836 is not a member of
that module.