<p>Urease (urea amidohydrolase, <db_xref db="EC" dbkey="3.5.1.5"/>) a nickel-binding enzyme that catalyses the hydrolysis of urea to form ammonia and carbamate [<cite idref="PUB00001363"/>]. It is mainly found in plant seeds, microorganisms and invertebrates. In plants, urease is a hexamer of identical chains, but the subunit composition of urease from different sources varies [<cite idref="PUB00010725"/>]; in bacteria [<cite idref="PUB00003605"/>] it consists of either two or three different subunits (alpha, beta and gamma).</p><p>Urease binds two nickel ions per subunit; four histidines, an aspartate and a carbamated-lysine serve as ligands to these metals; an additional histidine is involved in the catalytic mechanism [<cite idref="PUB00005206"/>]. The urease domain forms an (alpha beta)(8) barrel structure with structural similarity to other metal-dependent hydrolases, such as adenosine and AMP deaminase (see <db_xref db="PROSITEDOC" dbkey="PDOC00419"/>) and phosphotriesterase see <db_xref db="PROSITEDOC" dbkey="PDOC01026"/>). Urease is unique among nickel metalloenzymes in that it catalyses a hydrolysis rather than a redox reaction.</p><p>In <taxon tax_id="210">Helicobacter pylori</taxon>, the gamma and beta domains are fused and called the alpha subunit (<db_xref db="INTERPRO" dbkey="IPR008223"/>). The catalytic subunit (called beta or B) has the same organisation as the Klebsiella alpha subunit. Jack bean (<taxon tax_id="3823">Canavalia ensiformis</taxon>) urease has a fused gamma-beta-alpha organisation (<db_xref db="INTERPRO" dbkey="IPR008221"/>).</p><p>Urease (<db_xref db="EC" dbkey="3.5.1.5"/>) belongs to MEROPS peptidase family M38 (clan MJ).</p><p>This entry represents a region found in the urease alpha subunit UreC (designated the beta, or B chain, UreB in Helicobacter species) that contains two histidines that bind one of the nickel ions and the region of the active site histidine.</p> Urease, alpha subunit, conserved site