Band 3, the anion transporter, is conserved during evolution: implications for aging and vertebrate evolution.

A cDNA fragment corresponding to a highly evolutionarily conserved region of the major anion transport protein band 3 was cloned from lamprey mRNA using PCR homology probing. This is the first report providing evidence for a band-3 like transporter in the lowest vertebrates, the agnathostomes. Semi-quantitative PCR showed expression similar to that of higher vertebrates. Lamprey serum contains antibody-like molecules that bind to synthetic peptides of band 3 comprising senescent cell antigen, an aging antigen that terminates the life of cells. The high degree of homology found in nucleic acid and derived proteins sequence and the reaction of "antibodies" in lamprey serum with senescent cell antigen peptides of band 3 suggests that lamprey band 3 plays a role comparable to that in higher vertebrates.