SWE1 (YJL187C, UniProt P32944) — curation notes

2026-09-25 — first full review

Swe1 = S. cerevisiae Wee1 homologue, 819 aa, C-terminal kinase domain 444-794, ATP-binding Lys473,
catalytic Asp579 (UniProt features). Long, disordered, heavily phosphorylated N-terminal regulatory
region (UniProt lists >30 phosphosites, by Cdc28, Cdc5 and Cla4).
PANTHER PTHR11042:SF196; the family name is dominated by eIF2-alpha kinases (GCN2 is the fungal
cytoplasm-IBA donor). modules/g2_m_transition.yaml uses Swe1 as the budding-yeast Wee1 exemplar in the
wee1_kinase annoton (PAINT nodes PTN000113601, PTN008315181, PTN000867899).
UniProt gives EC 2.7.11.1 (Ser/Thr), whereas S. pombe wee1 carries EC 2.7.10.2 (Tyr). The
physiologically defined reaction is tyrosine phosphorylation of Cdc28 Tyr19.

Founding paper: PMID:8253069; PMID:8253069.
So: dispensable in an unperturbed cycle, opposed by Mih1 (Cdc25).
Morphogenesis checkpoint effector: PMID:8930890; the checkpoint monitors actin: PMID:9744879 and Lat-A arrest is Swe1-dependent PMID:9744879.
Localisation: PMID:10805747;
PMID:10805747;
PMID:10805747. The neck is where Swe1 is
inactivated/degraded; the nucleus is where it acts on Clb-Cdc28.
Feedback with its substrate: PMID:16096060
Cdc5 (Polo) interaction: PMID:11438652; Cdc5 overproduction modifies Swe1 and suppresses Swe1-dependent hsl1/hsl7
phenotypes. Later work (Asano 2005, Sakchaisri 2004 — not cached) shows Cla4 -> Clb2-Cdc28 -> Cdc5
sequential phosphorylation drives SCF(Met30)-dependent degradation (UniProt PTM section).

Meiosis: pachytene checkpoint PMID:10619027; 2026 update PMID:41927924, with zip1Δ swe1Δ genetics
PMID:41927924. Cdc5 drives
Swe1 degradation independently of CDK in meiosis (unlike mitosis).
SPB separation: PMID:8887667 — overexpression phenotype, downstream of Cdc28
Tyr19 inhibition.
Cell size: swe1Δ scored in the genome-wide size screen PMID:12089449; abstract does not name SWE1.
Harvey & Kellogg 2003 (PMID:12593792, not cached) show swe1Δ cells are smaller — real but modest effect
in budding yeast, where Start dominates size control.
Re-entry after G1 arrest: PMID:15107621,
and PMID:15107621.
Mechanism unknown.
Sphingolipids: PMID:26634277; orm1Δ orm2Δ
suppresses; cdc28-Y19F phenocopies swe1Δ; the Orm2-phosphorylation mechanism is "presumably"
PMID:26634277. Genetic, not biochemical; possibly routed through CDK.

ACCEPT (19): tyrosine kinase (IBA/IDA/IEA), protein kinase (HDA/IEA), ATP binding, nucleus (x4), bud
neck (x3), GO:0010972 IBA, GO:0044879 IDA+IMP, GO:0051598 IGI, GO:0110031 IBA, GO:0051447 IEA.
MODIFY (4): GO:0000086 IDA+IMP -> GO:0010972 (Swe1 opposes the transition; the negative-regulation
child is the accurate term). GO:0040020 IMP -> GO:0051598 / GO:0110031 (too general). GO:0106310 IEA
-> GO:0004674 (term usage note: serine-specific kinases only; Swe1 is dual-specificity/Tyr-directed;
same call as on human PKMYT1).
KEEP_AS_NON_CORE (10): cytoplasm IBA; Ser/Thr kinase IEA (EC); cell size HMP; re-entry IGI x3;
sphingolipid IMP + IGI x3.
MARK_AS_OVER_ANNOTATED (2): GO:0010697 negative regulation of SPB separation (IMP/IGI) — overexpression
readout of CDK inhibition, not a separate Swe1 process.
REMOVE (7): all bare GO:0005515 protein-binding IPI rows (Hsl7 x3, Cdc5 x2, Kin1, Cdc14) per repository
policy — interactions are real regulators OF Swe1 but no informative MF term for Swe1 follows from them.

Is Swe1 -> Orm2 phosphorylation direct? Would upgrade GO:0090154 from non-core if shown.
Should the UniProt EC be 2.7.10.2 (as for pombe wee1) rather than 2.7.11.1?
Nothing NEW proposed: the DNA-replication-stress and filamentous-growth roles (UniProt FUNCTION, papers
not cached) reuse the same Cdc28-Tyr19 activity and are not represented in GOA; not added without
cached primary evidence.