Deep research status: just deep-research-falcon mouse Serpinh1 --timeout 1800 --fallback perplexity-lite completed on 2026-05-03 and created Serpinh1-deep-research-falcon.md. Earlier short-timeout Falcon attempts failed before the required long run was used.
Core evidence: Serpinh1/Hsp47 is an ER-resident, collagen-specific protein folding chaperone. It is a serpin-family protein by fold, but the reviewed biology supports collagen chaperone activity rather than serine protease inhibitor activity.
Falcon synthesis: The Falcon report independently supports that SERPINH1/HSP47 is an ER-luminal collagen-specific chaperone that adopts a serpin fold but lacks serine protease inhibitory activity; it binds triple-helical procollagen/collagen in the ER, stabilizes collagen triple helices, prevents aggregation, and is retrieved to the ER after transient early secretory pathway transit [file:mouse/Serpinh1/Serpinh1-deep-research-falcon.md "SERPINH1 encodes HSP47, an ER-resident, collagen-specific molecular chaperone that adopts a serpin fold but lacks serine protease inhibitory activity"; file:mouse/Serpinh1/Serpinh1-deep-research-falcon.md "HSP47 binds triple-helical procollagen in the ER and stabilizes the triple helix"; file:mouse/Serpinh1/Serpinh1-deep-research-falcon.md "The dominant functional localization of SERPINH1/HSP47 is the ER lumen"].
Collagen-binding evidence: Koide et al. state that "The collagen binding chaperone HSP47 interacts with procollagen in the endoplasmic reticulum and plays a crucial role in the biosynthesis of collagen" and conclude that "HSP47 preferentially recognizes collagenous Gly-X-Y repeats in triple-helical conformation" PMID:10862616.
Knockout evidence: Nagai et al. state that "Hsp47 is an ER-resident stress inducible glycoprotein that specifically and transiently binds to newly synthesized procollagens" and that type I collagen "is unable to form a rigid triple-helical structure without the assistance of molecular chaperone Hsp47" PMID:10995453.
Developmental evidence: The chondrocyte conditional knockout supports cartilage and endochondral-bone phenotypes downstream of collagen maturation. These are valid non-core biological consequences of the collagen chaperone defect PMID:22492985.
Curation rule: GO:0004867 serine-type endopeptidase inhibitor activity should be removed for Serpinh1 despite the serpin fold. GO:0051082 unfolded protein binding should be modified to GO:0044183 protein folding chaperone because the supported activity is collagen-specific chaperoning.