An update on carbonic anhydrase-related proteins VIII, X and XI

Acatalytic Carbonic Anhydrases (CAs VIII, X, XI)

“…In the invertebrate group, CARP X-like proteins are present even in nematodes and insects. CARP XI, the last to be identified, was recognized only in tetrapod vertebrates (15,17). Recently, Parkkila and coworkers reported that there is no ortholog of CA11 in the known fish genomes, but instead there are two descendants of CA10, namely, CA10A and CA10B12.…”

“…Although the CARPs show a high degree of homology with the other known a-CA isoforms, they distinguish themselves from the catalytically active CAs by a salient feature: they lack one, two, or all three zinc protein ligands from the enzyme active site, that is, His94, His96, and His119 (the hCA I numbering system is used throughout this work) (15,(17)(18)(19). Figure 13.1 shows the sequence alignment of hCA II with CARP VIII, CARP X, and CARP XI (denominated from now on as hCAs VIII, IX, and XI, respectively).…”

“…In mammals, a-CA gene family consists of 13 isoforms that are catalytically active and 3 isoforms that are catalytically inactive lacking the CO 2 -hydratase activity as well as other known catalytic functions normally associated with these enzymes, such as the esterase activity (7,(10)(11)(12)(13)(14). Due to the high sequence and structural similarity with the active a-CAs, these proteins have been designated as CA-related proteins (CARPs) and were originally identified by screening Purkinje cell-specific genes (7,(15)(16)(17)(18). The three mammalian CARPs are named as CARP VIII, CARP X, and CARP XI.…”

“…In the family of protein tyrosine phosphatases (PTPs), there are two receptor-type PTPs, -PTPR and g-PTPR, also containing an N-terminal CA-like domain, called "CARP XVI domain" (15,17).…”

Carbonic Anhydrase XIII

“…The a-CAs are divided into groups depending on their subcellular localization and activity: the CA isozymes I, II, III, VII, and XIII are located in cytoplasm; CAs IV, IX, XII, XIV, XV, and XVII are membrane-bound; CAs VA and VB are mitochondrial; CA VI is secreted; and the CA-related proteins (CARPs) CARP VIII, CARP X, and CARP XI are acatalytic, soluble proteins (3)(4)(5)(6)(7). The exact number of active CA isozymes varies between species due to gene duplications and losses.…”