Non-catalytic component of the NSL histone acetyltransferase complex, a multiprotein complex that mediates histone H4 acetylation at 'Lys-5'- and 'Lys-8' (H4K5ac and H4K8ac) at transcription start sites and promotes transcription initiation (PubMed:20018852, PubMed:22547026, PubMed:33657400). The NSL complex also acts as a regulator of gene expression in mitochondria (PubMed:27768893). In addition to its role in transcription, KANSL1 also plays an essential role in spindle assembly during mitosis (PubMed:26243146). Associates with microtubule ends and contributes to microtubule stability (PubMed:26243146). {ECO:0000269|PubMed:20018852, ECO:0000269|PubMed:22547026, ECO:0000269|PubMed:26243146, ECO:0000269|PubMed:27768893, ECO:0000269|PubMed:33657400}. This is the function of KANSL1 (KAT8 regulatory NSL complex subunit 1, Ensembl gene identifier ENSG00000120071).