N-TERMINAL PROTEIN-SEQUENCE ANALYSIS OF THE RABBIT ERYTHROCYTE LACTATE TRANSPORTER SUGGESTS IDENTITY WITH THE CLONED MONOCARBOXYLATE TRANSPORT PROTEIN MCT1
Rc. Poole et Ap. Halestrap, N-TERMINAL PROTEIN-SEQUENCE ANALYSIS OF THE RABBIT ERYTHROCYTE LACTATE TRANSPORTER SUGGESTS IDENTITY WITH THE CLONED MONOCARBOXYLATE TRANSPORT PROTEIN MCT1, Biochemical journal, 303, 1994, pp. 755-759
An improved purification for the rabbit erythrocyte lactate transporte
r, using aminoethyl-Sepharose chromatography, is described. The proces
s of purification of the 40-50 kDa transporter, labelled with 4,4'-dii
sothiocyanostilbene-2,2'-disulphonate (DIDS), was followed by Western
blotting with anti-DIDS antibodies [Poole, R. C. and Halestrap, A, P.
(1992) Biochem. J. 283, 855-862]. Fractions highly-enriched in transpo
rter were further purified by SDS/PAGE and the 40-50 kDa DIDS-labelled
polypeptide was subjected to N-terminal protein sequencing. This anal
ysis identified the first 16 amino acids of the protein. With the exce
ption of one conservative substitution, this protein sequence is ident
ical to the N-terminal protein sequence predicted from a cDNA isolated
from Chinese hamster ovary cells that encode a monocarboxylate transp
orter, MCT1 [Kim Garcia, C., Goldstein, J. L., Pathak, R.K., Anderson,
R. G. W. and Brown, M. S. (1994) Cell 76, 865-873]. This observation,
along with similarities in functional properties, leads us to conclud
e that lactate transport in rabbit erythrocytes is mediated by the MCT
1 monocarboxylate transporter isoform.