Characterisation of the H(+)/peptide cotransporter of eel intestinal brush-border membranes.
J Exp Biol
; 203(Pt 19): 2991-3001, 2000 Oct.
Article
em En
| MEDLINE
| ID: mdl-10976035
ABSTRACT
H(+)/peptide cotransport in brush-border membrane vesicles (BBMVs) from eel (Anguilla anguilla) intestine was studied by measuring d-[(3)H]-phenylalanyl-l-alanine uptake and by monitoring peptide-dependent intravesicular acidification using the pH-sensitive dye Acridine Orange. d-[(3)H]-phenylalanyl-l-alanine influx was greatly stimulated by an inside-negative membrane potential and enhanced by an inwardly directed H(+) gradient. In parallel, vesicular H(+) influx was significantly increased in the presence of extravesicular d-phenylalanyl-l-alanine or a series of glycyl and l-prolyl peptides. H(+)/peptide cotransport displayed saturable kinetics involving a single carrier system with apparent substrate affinities of 0.9-2.6 mmol l(-1) depending on the particular peptide. All substrates tested competed with this system. Pre-incubation of BBMVs with dipeptides prevented diethylpyrocarbonate inhibition of transport activity, suggesting that the substrates mask histidine residues involved in the catalytic function of the transporter. Using human PepT1-specific primers, a reverse transcription-polymerase chain reaction (RT-PCR) signal was detected in eel intestine. Our results suggest that, in eel intestine, a brush-border membrane 'low-affinity'-type H(+)/peptide cotransport system is present that shares kinetic features with the mammalian intestinal PepT1-type transporters.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Membrana Transportadoras
/
Proteínas de Transporte
/
Caderinas
/
Simportadores
/
Mucosa Intestinal
/
Anguilla
Tipo de estudo:
Clinical_trials
Limite:
Animals
/
Humans
Idioma:
En
Revista:
J Exp Biol
Ano de publicação:
2000
Tipo de documento:
Article
País de afiliação:
Itália