CHS1 (YNL192W, P08004) notes

• Class I chitin synthase, EC 2.4.1.16, 7 TM, zymogen requiring proteolytic activation [UniProt:P08004].
• Repair/auxiliary enzyme: chs1 null buds lyse at acidic pH due to chitinase damage at the birth scar PMID:2523889; cannot replace Chs2 in septum formation PMID:2523889
• Localization: plasma membrane and chitosomes PMID:7952171; PMID:8970154
• QRRRW arginine mutations in Chs1 abolish activity PMID:9760183.

Curation decisions: 'septum digestion after cytokinesis' IMP marked over-annotated (Chs1 repairs, not digests). Cytosol RCA removed. Hexosyltransferase IEA -> chitin synthase activity.