Hypoxia-inducible factor-1, α-subunit, HIF1α of 826 aas and from 0 to about 2 possible TMSs.  The structure and functions have been considered (Iyer et al. 1998).  This protein may regulate L-type Ca²⁺ channels in response to hypoxia (see family description (Moreno-Domínguez et al. 2024).  It functions as a master transcriptional regulator of the adaptive response to hypoxia (Xu et al. 2018).  Under hypoxic conditions, it activates the transcription of over 40 genes, including erythropoietin, glucose transporters, glycolytic enzymes, vascular endothelial growth factor, HILPDA, and other genes whose protein products increase oxygen delivery or facilitate metabolic adaptation to hypoxia (Xu et al. 2018).