Evaluation of and recommendation for the nomenclature of the CPB2 gene product (also known as TAFI and proCPU): Communication from the SSC of the ISTH

The CPB2 gene product was discovered independently byvarious groups in the early to mid-1990s and as a resulthas been assigned different names by each laboratory. In1989, Hendriks et al. [1,2] described a labile enzyme thatinterfered with their assay for carboxypeptidase N. A yearlater, he and co-workers assigned this enzyme the namecarboxypeptidase U, with ‘U’ symbolizing unstable, afundamental property of the enzyme [3]. Within a fewyears, the CPB2 gene product (this term is used through-out to avoid bias) came to be referred to by many othernames, including plasma carboxypeptidase B [4] and car-boxypeptidase R [5]. The regulatory role of the CPB2gene product in fibrinolysis was not fully appreciateduntil 1995, when Bajzar, Manuel and Nesheim describedthe purification and characterization of a carboxypepti-dase zymogen that was activated by thrombin [6]. Theytermed this novel fibrinolytic inhibitor ‘thrombin activat-able fibrinolysis inhibitor’ (TAFI), another widely usedsynonym for the CPB2 gene product. More recently,additional roles of the CPB2 gene product have beendescribed, including its ability to regulate inflammation.As a result, additional names such as thrombin-activata-ble carboxypeptidase B [7] and carboxypeptidase B2 [8]have been assigned to the CPB2 gene product, furthercomplicating the literature. The lack of uniformity of theCPB2 gene product nomenclature has raised issues con-cerning literature searches and prompted the Scientificand Standardization Committee (SSC) on fibrinolysis toassess whether the fibrinolysis community is willing toharmonize the CPB2 gene product nomenclature.