air-2 (O01427, AIR2_CAEEL): manual literature synthesis

No deep-research provider was run for this gene (no API keys in the session). This
synthesis was written by hand from the cached publications in publications/, the
UniProt record (air-2-uniprot.txt) and GO term lookups (QuickGO/OLS). Each claim
carries its source.

Identity and family

• AIR-2 (Aurora/Ipl1-related kinase 2; also stu-7) is the single C. elegans Aurora B
  kinase, 305 aa, a member of the Ser/Thr protein kinase family, Aurora subfamily
  (UniProt SIMILARITY, PROSITE-ProRule PRU00159). Its paralog AIR-1 is the Aurora A
  kinase that sits on centrosomes PMID:9852156.
• stu-7 mutants, later shown to be air-2 alleles, are defective in post-embryonic and
  embryonic chromosome segregation but not in centrosome separation or bipolar spindle
  assembly PMID:10354474.

Chromosomal passenger complex

• AIR-2 is the catalytic subunit of the C. elegans CPC with ICP-1 (INCENP), BIR-1
  (survivin) and CSC-1 (borealin-like) PMID:12707312. ICP-1 is the activator; CSC-1/BIR-1 are targeting subunits
  PMID:12707312.
• Positive feedback: AIR-2 phosphorylates two adjacent serines in the ICP-1 C-terminus,
  and this phosphorylation is needed for ICP-1 to stimulate AIR-2 PMID:12048181.
• BIR-1 is required for AIR-2 chromosome localization PMID:10983970.
• Other regulators: TLK-1 is both substrate and activator (ICP-1-dependent)
  PMID:15916946; CDC-48.3 binds AIR-2 directly and inhibits its activity from metaphase
  to telophase PMID:18854144; LAB-1, via GSP-2/PP1, restricts AIR-2 to the
  interface between homologs in meiosis PMID:18923084; PP1 (GLC-7alpha/beta)
  antagonizes AIR-2 [PMID:11940606, PMID:10975519]; AIR-2 is SUMO-modified in vitro
  in a GEI-17-dependent manner PMID:25475837.

Kinase activity and substrates (direct, in vitro)

• REC-8 (meiotic cohesin) PMID:11940606
• ICP-1 (INCENP) C-terminal serines PMID:12048181.
• BMK-1 (BimC kinesin) C-terminal tail PMID:15548597.
• ZEN-4/MKLP1 C-terminal serines, in vitro and in vivo PMID:15854913.
• TLK-1 Ser634 [PMID:15916946; UniProt FUNCTION].
• KLP-7 (kinesin-13) N-terminal region, with ICP-1 as co-activator PMID:26168236.
• Histone H3 Ser10: AIR-2 is required for mitotic H3 phosphorylation; in vivo
  requirement rather than a cached in vitro assay [PMID:10975519 "both enzymes are
  required for H3 phosphorylation and chromosome segregation"; PMID:10983970].

Localization

• Meiotic and mitotic chromosomes; in meiosis restricted to the mid-bivalent region
  (last points of contact between homologs, then sisters) [PMID:9852156; PMID:11940606;
  PMID:18923084].
• In mitosis on metaphase chromosomes, then central spindle/midzone in anaphase, then
  midbody, where it persists [PMID:9852156 "AIR-2 is found on metaphase chromosomes,
  moves to midbody microtubules at anaphase, and then persists at the cytokinesis
  remnant"; PMID:23684975; PMID:25475837].
• In meiosis the CPC lies in the gap between the kinetochore cups, i.e. not on the
  kinetochore itself PMID:20729837.
• Not centrosomal (contrast with AIR-1) PMID:9852156.

Biological roles

• Mitotic chromosome segregation and metaphase congression [PMID:10983970;
  PMID:11050384; PMID:12707312].
• Meiotic chromosome separation: required for REC-8 release and homolog/sister
  separation at both meiotic anaphases PMID:11940606.
• Recruitment of the ring-domain network (BUB-1 and downstream) in meiosis, and
  microtubule assembly between separating meiotic chromosomes PMID:20729837.
• Cytokinesis: furrows initiate and regress; AIR-2 acts at metaphase/early anaphase to
  localize ZEN-4, in a pathway parallel to CYK-1 [PMID:9852156; PMID:11050384];
  phosphorylation of ZEN-4 by AIR-2 is needed for completion of cytokinesis
  PMID:15854913. AIR-2 is also required for localization of BMK-1 to spindles
  PMID:15548597 and of CDC-14 to the central spindle PMID:12213836.
• Chromatin bridges hyperactivate AIR-2 at the midzone/midbody, which recruits
  condensin I and prevents furrow regression PMID:23684975.
• Condensin SMC-4 loading on mitotic chromosomes requires AIR-2 [PMID:11914278,
  abstract only; via UniProt FUNCTION].

Not supported in C. elegans

• Spindle assembly checkpoint function and positive regulation of mitotic sister
  chromatid separation: asserted by ComplexPortal (NAS, PMID:12707312) by analogy; no
  worm data examined in cached literature.
• Centrosome/spindle pole localization: Aurora A (AIR-1) property, not AIR-2.