Related Experiment Video
Updated: Aug 19, 2026
Methods to Study Epithelial Transport Protein Function and Expression in Native Intestine and Caco-2 Cells Grown in 3D
Published on: March 16, 2017
Developmental regulation of a turkey intestinal peptide transporter (PepT1)
L Van1, Y X Pan, J R Bloomquist
1Department of Animal and Poultry Sciences (0306), Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.
Insights
Researchers identified a novel turkey intestinal peptide transporter, tPepT1, crucial for nutrient absorption. Its gene expression significantly increases during turkey embryonic development, highlighting its importance for neonatal poults.
Area of Science:
- Molecular Biology
- Animal Physiology
- Genetics
Background:
- Peptide transporters play a vital role in nutrient absorption in the small intestine.
- Understanding avian peptide transporters is essential for poultry science and nutrition.
- The specific role of peptide transporters in turkey development was previously uncharacterized.
Purpose of the Study:
- To isolate and characterize the turkey intestinal peptide transporter, tPepT1.
- To investigate the transport kinetics and substrate specificity of tPepT1.
- To examine the developmental regulation of tPepT1 gene expression in turkey embryos.
Main Methods:
- cDNA library screening to isolate the tPepT1 gene.
- Xenopus oocyte expression system with two-electrode voltage-clamp electrophysiology.
- Northern blot analysis to quantify mRNA levels in developing turkey embryos.
Main Results:
- Isolated tPepT1 cDNA encodes a 714-amino acid protein with high homology to chicken PepT1.
- tPepT1 facilitates pH-dependent, Na+-independent transport of dipeptides (Gly-Sar, Met-Met) with high affinity.
- PepT1 mRNA abundance increased 3.2-fold in the small intestine from 5 days before hatching to the day of hatch.
Conclusions:
- tPepT1 is a functional peptide transporter in turkeys, sharing characteristics with orthologs in other species.
- PepT1 exhibits high affinity for dipeptides and potential substrate inhibition by larger peptides.
- PepT1 gene expression is developmentally regulated in turkey embryos, suggesting a critical role in neonatal intestinal function and nutrient uptake.
Abstract:
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.
Related Concept Videos
01:06Carrier-Mediated Transport
Active transport involves two types of membrane-spanning transporters: uptake and efflux. Uptake transporters are expressed in the small...
01:12Role Of Notch Signalling In Intestinal Stem Cell Renewal
Direct cell-to-cell contact is needed for the activation of Notch signaling. The signal is initiated when a notch ligand binds to a receptor on an adjacent cell, also...
01:23Renewal of Intestinal Stem Cells
01:22Role of Ephrin-Eph Signalling in Intestinal Stem Cell Renewal
01:26Insertion of Single-pass Transmembrane Proteins in the RER
Integral transmembrane proteins possess transmembrane and extra membrane domains. The transmembrane domains are primarily made of 20-25 hydrophobic amino acids arranged in a helical secondary confirmation. These...
01:20Cotranslational Protein Translocation
Sec61 channel partners for cotranslational translocation
During cotranslational translocation, the Sec61 channel partners with the signal recognition particle (SRP), the signal recognition particle receptor (SR), and the ribosomes to transport the nascent polypeptide chain...