Eva-1 Homolog C (EVA1C)

A supernumerary copy of human chromosome 21 (HC21) causes Down syndrome. To understand the molecular pathogenesis of Down syndrome, it is necessary to identify all HC21 genes. Human C21orf63 is a type-1 transmembrane protein of hitherto unknown function, with two repeats of putative ‘galactose-binding lectin domains'. Human C21orf63 interacts with heparin and to a lesser extent with heparan sulphate. The C-terminal galactose-binding lectin domain of C21orf63 is necessary for heparin binding. The inability of other human proteins with galactose-binding lectin domains to interact with heparin suggests that heparin binding is a unique property of C21orf63. Results of real-time polymerase chain reaction and tissue immunostaining imply that C21orf63 is expressed on epithelia of various human tissues.