EGLN2/PHD1: ProductsEGLN2 (EGL/EGg Laying-Nine #2; also known as PHD1 and HPH3) is a 43 kDa member of the EglN family of proteins. It is ubiquitously expressed and found principally in the nucleus. EGLN2 hydroxylates proline on HIF-1 alpha. HIF-1 is an alpha/beta heterodimeric transcriptional activator that upregulates genes involved in mitigating the effects of hypoxia. Normally, and in the presence of abundant oxygen, the HIF-1 alpha-chain is hydroxylated by PHD family members, which results in its ubiquitylation and degradation. Under low oxygen tension, EGLN2 activity is decreased, the HIF-1alpha subunit is retained, and HIF-1 activates genes. Human EGLN2 is 407 amino acids (aa) in length (SwissProt #: Q96KS0). It contains one iron 2-oxoglutarate (Fe2OG) dioxygenase domain (aa 278-376) plus an iron-binding (His297 and His358), and a 2-oxoglutarate-binding (Arg367) site. There is one alternative start site at Met34 that generates a 40 kDa isoform. In addition, there is another potential splice form that shows a 16 aa substitution for aa 1-281. Full-length human EGLN2 shares 91% aa sequence identity with mouse EGLN2.