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Role of rhodopsin N-terminus in structure and function of rhodopsin-bitter taste receptor chimeras

Sai Prasad Pydi1, Raja Chakraborty, Rajinder Pal Bhullar

  • 1Department of Oral Biology, University of Manitoba, and The Manitoba Institute of Child Health, Winnipeg MB, Canada R3E 0W4.

Biochemical and Biophysical Research Communications
|November 20, 2012
PubMed

Insights

Adding rhodopsin N-terminal sequences to bitter taste receptors (T2Rs) can improve their expression. Specifically, 33 amino acids enhance T2R4 expression without altering its structure or function.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Pharmacology

Background:

  • Bitter taste receptors (T2Rs) are G protein-coupled receptors (GPCRs) crucial for human bitter taste sensation.
  • Low expression levels of T2Rs hinder structure-function studies.
  • Rhodopsin N-terminal sequences are often used to enhance T2R expression in heterologous systems.

Purpose of the Study:

  • To investigate the impact of different lengths of rhodopsin N-terminal sequences on the structure and function of the bitter taste receptor T2R4.
  • To characterize potential local structural perturbations and their effects on receptor function and allosteric ligand binding.

Main Methods:

  • Construction of chimeric T2R4 receptors incorporating rhodopsin N-terminal sequences (33 and 38 amino acids) based on molecular models.
  • Functional characterization using calcium imaging assays.
  • Quantification of receptor expression levels via flow cytometry.

Main Results:

  • The insertion of 33 amino acids from the rhodopsin N-terminus significantly enhanced T2R4 expression by 2.5-fold.
  • This enhancement in expression was achieved without inducing detectable perturbations in the T2R4 receptor structure.
  • The functional integrity of T2R4 was maintained with the added sequence.

Conclusions:

  • The N-terminal 33 amino acids of rhodopsin serve as an effective tool to improve the expression of bitter taste receptor T2R4.
  • This strategy facilitates further structure-function studies of T2Rs, overcoming expression limitations.
  • The findings suggest that specific N-terminal modifications can enhance GPCR expression without compromising receptor integrity.

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