Where do tertiary base pair interactions largely map onto the three-dimensional structure of tRNA? What is their purpose?

Tertiary base pair interactions in tRNA largely map onto the three-dimensional structure within the core region of the molecule. These interactions help stabilize the overall structure of tRNA, enabling it to carry out its essential role in protein synthesis.

To understand where these interactions occur, you can refer to the secondary and tertiary structure of tRNA. The secondary structure of tRNA is characterized by a cloverleaf shape, formed by specific base pairing interactions between different regions of the molecule. The tertiary structure of tRNA then arises from additional folding and base pairing interactions.

Within the tertiary structure, the majority of tertiary base pair interactions are found in the anticodon loop, the D loop, and the TψC arm of tRNA. These interactions involve specific hydrogen bonding patterns between the bases, which contribute to the stability and precision of tRNA structure.

The purpose of these tertiary base pair interactions is to ensure the accuracy and functionality of tRNA in protein synthesis. They play several key roles:

1. Stabilization: Tertiary base pair interactions contribute to the overall stability of tRNA, helping it resist structural perturbations and maintain its functional shape.

2. Codon recognition: The anticodon loop, which contains tertiary base pair interactions, is responsible for recognizing and base pairing with the complementary codon on mRNA during translation. The precise interactions in this region ensure the accurate recognition of the codon and help prevent misreading of the genetic code.

3. Aminoacyl-tRNA recognition: Tertiary interactions within the D loop and the TψC arm contribute to the correct recognition of specific aminoacyl-tRNA synthetases. These enzymes ensure that the appropriate amino acid is attached to the correct tRNA molecule, allowing for accurate protein synthesis.

In summary, tertiary base pair interactions in tRNA are primarily located in the anticodon loop, the D loop, and the TψC arm. Their purpose is to stabilize the structure of tRNA and enable accurate codon recognition and aminoacyl-tRNA recognition during protein synthesis.