Developmental regulation of a turkey intestinal peptide transporter (PepT1).
A cDNA encoding a turkey intestinal peptide transporter, tPepT1, was isolated from a turkey small intestinal cDNA library. The tPepT1 cDNA encodes a 714-amino acid protein with 12 predicted transmembrane domains. The amino acid sequence of tPepT1 is 94.3% identical to chicken PepT1 and approximately 60% identical to PepT1 from rat, sheep, rabbit, and human. Using a 2-electrode voltage-clamp technique in Xenopus oocytes expressing tPepT1, Gly-Sar transport was pH dependent but was independent of Na+ and K+. For the dipeptides Gly-Sar and Met-Met, the evoked inward currents indicated that the transporter was saturable and had high affinity (0.69 +/- 0.14 mM and 0.23 +/- 0.04 mM, respectively) for these substrates. However, transport of the tetrapeptide, Met-Gly-Met-Met, exhibited apparent substrate inhibition at high substrate concentrations. To study developmental regulation of PepT1 mRNA in turkey embryos, embryos (6 males and 6 females) were sampled daily from 5 d before hatch to the day of hatch (d 0). The abundance of PepT1 mRNA in the small intestine was quantified densitometrically from Northern blots after hybridization with full-length tPepT1 cDNA as probe. A 3.2-fold increase in PepT1 mRNA was observed in intestinal tissue from 5 d before hatch to d 0. This increase in PepT1 mRNA abundance indicates that the PepT1 gene is developmentally regulated and that there may be an important role for PepT1 in the neonatal poult.
Van
L
L
Department of Animal and Poultry Sciences (0306), Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.
Pan
Y X
YX
Bloomquist
J R
JR
Webb
K E
KE
Wong
E A
EA
D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D007422:Intestines / Q000737:chemistry / Q000196:embryology; D008297:Male; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D018408:Patch-Clamp Techniques; D012333:RNA, Messenger / Q000032:analysis; D016415:Sequence Alignment; D014162:Transfection; D014422:Turkeys / Q000196:embryology / Q000235:genetics*; D014981:Xenopus
D026901:Membrane Transport Proteins; D012333:RNA, Messenger; C067802:intestinal peptide-proton cotransporter