asr1 (O94400) relative comparison

Script: compare_relatives.py (run with uv run --script compare_relatives.py); raw output in
compare_relatives_results.json. Sequences are fetched live from UniProt REST.

Method: Smith-Waterman local alignment, BLOSUM62, gap open -11, extend -1; z-score against 200
shuffles of the second sequence.

PANTHER placement (PANTHER 19.0 classification files)

S. pombe asr1 O94400: PTHR12618:SF20 (PHD AND RING FINGER DOMAIN-CONTAINING PROTEIN 1)
Human PHRF1 Q9P1Y6: PTHR12618:SF20
K. phaffii Atg35 C4QVX6: PTHR12618:SF20
S. cerevisiae Asr1 Q06834: PTHR45798:SF97 (family RING-H2 FINGER PROTEIN ATL61-RELATED-RELATED), a different PANTHER family

S. cerevisiae has no PTHR12618 member in the PANTHER 19.0 budding-yeast file.

Pairwise results

Pair	identity	aligned columns	range in first	range in second	z
O94400 vs Q06834 (Sc Asr1)	0.326	95	56-152	23-148	14.0
O94400 vs Q9P1Y6 (PHRF1)	0.319	276	34-318	104-420	28.2
O94400 vs C4QVX6 (Atg35)	0.287	363	55-545	21-387	22.7
Q06834 vs Q9P1Y6	0.288	191	2-233	106-301	17.0
Q06834 vs C4QVX6	0.314	140	1-183	1-141	13.6
O94400[1-200] vs Q9P1Y6	0.384	125	34-167	104-230	39.0

Interpretation

All four proteins share a homologous N-terminal RING + PHD module (all z > 13). O94400 is
more similar to the PTHR12618:SF20 members PHRF1 and Atg35 than to S. cerevisiae Asr1, and its
similarity to Asr1 is confined to the RING/PHD region. Sc Asr1 is homologous to the SF20 members
over the same module, so its placement in a separate PANTHER family (PTHR45798, plant ATL-type
RING-H2 proteins) looks like a divergent sequence classified by its RING alone. Pairwise scores do
not resolve orthology; the PomBase asr1-ASR1 ortholog call is consistent with the shared module
but is not confirmed by PANTHER. Only properties of the shared RING module (E3 ubiquitin ligase
activity) are safe to transfer; Asr1-specific features such as Ser5P/Ser7P CTD recognition are not.