Hydroxymethylbilane Synthase (HMBS) Human Recombinant Protein

This gene encodes a member of the hydroxymethylbilane synthase superfamily. The encoded protein is the third enzyme of the heme biosynthetic pathway and catalyzes the head to tail condensation of four porphobilinogen molecules into the linear hydroxymethylbilane. Mutations in this gene are associated with the autosomal dominant disease acute intermittent porphyria. Alternatively spliced transcript variants encoding different isoforms have been described. [provided by RefSeq, Jul 2008]

HMBS: Tetrapolymerization of the monopyrrole PBG into the hydroxymethylbilane pre-uroporphyrinogen in several discrete steps. Defects in HMBS are the cause of acute intermittent porphyria (AIP). AIP is a form of porphyria. Porphyrias are inherited defects in the biosynthesis of heme, resulting in the accumulation and increased excretion of porphyrins or porphyrin precursors. They are classified as erythropoietic or hepatic, depending on whether the enzyme deficiency occurs in red blood cells or in the liver. AIP is an autosomal dominant form of hepatic porphyria characterized by acute attacks of neurological dysfunctions with abdominal pain, hypertension, tachycardia, and peripheral neuropathy. Most attacks are precipitated by drugs, alcohol, caloric deprivation, infections, or endocrine factors. Belongs to the HMBS family. 2 isoforms of the human protein are produced by alternative splicing.

Protein type: Cofactor and Vitamin Metabolism - porphyrin and chlorophyll; EC 2.5.1.61; Mitochondrial; Transferase

Chromosomal Location of Human Ortholog: 11q23.3

Cellular Component: cytosol

Molecular Function: hydroxymethylbilane synthase activity

Biological Process: porphyrin metabolic process; protoporphyrinogen IX biosynthetic process; peptidyl-pyrromethane cofactor linkage; heme biosynthetic process

Disease: Porphyria, Acute Intermittent