Characterization of a novel mAb against bilitranslocase - a new biomarker of renal carcinoma

Abstract

Bilitranslocase (TC 2.A.65.1.1) is a bilirubin-specific membrane transporter, found on absorptive (stomach and intestine) and excretory (kidney and liver) epithelia and in the vascular endothelium.

A segment AA 58-99 of bilitranslocase primary structure is highly homologous to an invariant segment present in the α-chain of phycocyanins, light-harvesting proteins, occurring in cyanobacteria. Polyclonal antibodies have been raised in rabbits in the past, using a synthetic peptide corresponding to AA 67-75 of rat liver bilitranslocase, bound to KLH as an antigen. Affinity-purified antibodies from immune sera have been found to inhibit various membrane transport functions, including bilirubin uptake into human hepatocytes and uptake of some flavonoids into human vascular endothelial cells.

In this article we show an immunological approach, based on newly developed monoclonal antibodies, to a detailed biochemical and functional characterization of a protein whose gene and protein structure is still unknown. We were able to demonstrate our novel mAb as a tumor marker candidate of renal cell carcinoma, which may prove useful in the diagnostic procedures.