The diagram below represents general structure of glutamate

The diagram below represents general structure of glutamate receptor. Use this diagram to discuss the levels of protein structure and the bonds maintaining each level. What is protein domain?

membrane glutamate binding site agonist binding domain: structurally related to bacterial periplasmic amino acid binding proteins cystein-rich region seven-transmembrane domains intracellular regions controlling G-protein coupling and receptor localization

Solution

Proteins are the complex macromolecules which acts as building blocks of human body. They are made up of amino acids. There are four levels of protein structure are as follows:

1. Primary structure: Primary structure refers to the linear arrangement of aminoacids. Peptide bonds holds the adjacent aminoacids in a polypeptide chain.

2. Secondary structure: Secondary structure refers to highly regular local sub-structure on the actual polypeptide backbone chain. A local region of polypeptide chain may fold into a alpha helix or a beta sheet. These secondary structures are defined by patterns of hydrogen bonds between the main-chain peptide groups. They have a regular geometry, being constrained to specific values of the dihedral angles and on the Ramachandran plot. In secondary structure, hydrogen bonds holds the structure of protein.

3. Tertiary structure: Tertiary structure refers to the 3-D structure of the protein molecule. The alpha helix and the beta sheets are folded into a compact globular structure. The folding is done by non-specific hydrophobic interactions.

4. Quaternery Structure: Some proteins have quaternery structure, that means they have two polypeptide chains. Each polypeptide chain in such a protein is called subunit. It is stabilized by non-covalent interactions and disulfide bonds

Domain: A structural domain is an element of the protein\'s overall structure that is self stabilizing and often folds independently of the rest of the protein chain. Many domains are not unique to the protein products of one gene or one gene family but instead appear in a variety of proteins.