ASSOCIATION OF HSP60-LIKE PROTEINS WITH THE L-SYSTEM AMINO-ACID TRANSPORTER

The carrier protein(s) responsible for mammalian L-system amino acid t ransport has not been identified, Chronic lymphocytic leukemia (CLL) B -lymphocytes have markedly diminished L-system transport which is rest ored after treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA). Six candidate L-system related plasma membrane proteins were identifie d in TPA-treated CLL-cells using an L-system photoprobe and ultra-high -resolution two-dimensional gel electrophoresis, In the current studie s, two candidate L system related proteins were obtained from preparat ive giant two dimensional gels, and the amino acid sequences of peptid e fragments from these proteins were determined by Edman degradation, These proteins, forming a doublet on the gels at an apparent size of 4 0 kDa and pI 5.85, had sequence homology to the mitochondrial heat sho ck protein 60 (hsp60). The presence of these proteins in CLL lymphocyt e plasma membranes was confirmed by immunoblotting with antibodies to hsp6O. These observations indicate that an hsp60 homologue is associat ed with the L-system amino acid transporter. (C) 1997 Academic Press.