This is manually authored research based on the original sources and official records listed in the source guide. Automated Falcon and perplexity-lite attempts failed; this file is not provider output.
Human XPB directly hydrolyzes ATP. Recombinant GST-XPB in PMID:8663148 and human XPB/TFIIH mutant experiments in PMID:17466626 separate hydrolysis from directional strand unwinding. In the latter study, p52 stimulates the XPB ATPase; XPB is the activated motor. Human TFIIH repair reconstruction in PMID:41673165 places XPB motor action in bubble enlargement, using a Cy5 lesion mimic and separate XPB/XPD ATPase mutants. This establishes a repair motor contribution, not selective recognition of chemically damaged DNA or nuclease chemistry. Local DNA opening also does not demonstrate the change in linking number required by GO:0006265.
Human HeLa TFIIH purification and reconstitution support XPB membership in TFIIH core and holo-complexes. PMID:27193682 uses TBP in place of TFIID and positions XPB on downstream duplex DNA in initiation assemblies; static structural displacement is not real-time motor stepping. Initiation and promoter clearance are separate phases in current GO. Human HAP1 depletion/PRO-seq in PMID:35947745 supports heterogeneous dependence across promoters, with residual protein and depletion-versus-inhibition limits.
The actual XPC–HR23B recruitment experiments in PMID:10734143 distinguish direct XPC–GST-XPB binding from HR23B recovery through the XPC complex. Human TTDA/XPD association with XPB is supported by controlled co-immunoprecipitation in PMID:16669699. PMID:9173976 separately assays human XPB with mouse Sug1 and endogenous human SUG1 complexes. Large interaction datasets establish specific experimental pairs, with physiological roles left open. Human XPB patient-cell studies support contextual UV-response, p53-apoptosis and checkpoint effects; these do not define a separate universal apoptosis machinery function.
The actual PAINT tree, MSA and IBD target paths support conserved TFIIH functions. Rat organogenesis expression and the inaccessible hair-dysplasia review do not establish precise developmental steps. Official UniProt provides one 782-aa natural sequence and no alternative-product list. Assay fragments or tagged mutants remain experimental constructs. The source guide records exact organism, host, construct, target-table and access boundaries for each retained or unresolved assertion.