Hewett-Emmett D, Tashian R E
Human Genetics Center, University of Texas Health Science Center at Houston 77225, USA.
Mol Phylogenet Evol. 1996 Feb;5(1):50-77. doi: 10.1006/mpev.1996.0006.
The carbonic anhydrases (CA) catalyze with high efficiency the reversible hydration of carbon dioxide, a reaction underlying many diverse physiological processes in animals, plants, archaebacteria, and eubacteria. We examined the evolutionary history and functional convergence of the CAs encoded by members of three independent CA gene families (alpha-CA, beta-CA and gamma-CA). Surprisingly, the six mammalian alpha-CA isozymes of defined function and tissue expression are evolving more rapidly than four mammalian alpha-CA-related proteins of unknown function. We have identified and included several previously unrecognized CA homologues present in the sequence databases, many of which are the fruits of genome project sequencing and expressed cDNA studies. We examined alpha-CA active site evolution and the putative beta-CA and gamma-CA active sites. We found support for the "introns late" hypothesis by analysis of alpha-CA intron locations. The view that alpha-CAs would be restricted to the animal kingdom and plant green algae (Chlamydomonas), the beta-CAs to plants and eubacteria, and the gamma-CAs to archaebacteria and eubacteria is breaking down. The plant Arabidopsis has homologues of all three families.
碳酸酐酶（CA）高效催化二氧化碳的可逆水合反应，该反应是动物、植物、古细菌和真细菌中许多不同生理过程的基础。我们研究了三个独立的CA基因家族（α-CA、β-CA和γ-CA）成员所编码的CA的进化历史和功能趋同。令人惊讶的是，具有明确功能和组织表达的六种哺乳动物α-CA同工酶的进化速度比四种功能未知的哺乳动物α-CA相关蛋白更快。我们在序列数据库中鉴定并纳入了几种先前未被识别出的CA同源物，其中许多是基因组计划测序和表达cDNA研究的成果。我们研究了α-CA活性位点的进化以及假定的β-CA和γ-CA活性位点。通过对α-CA内含子位置的分析，我们发现了对“内含子晚期”假说的支持。认为α-CA仅限于动物界和植物绿藻（衣藻）、β-CA仅限于植物和真细菌、γ-CA仅限于古细菌和真细菌的观点正在被打破。植物拟南芥具有所有这三个家族的同源物。
