Question

How many polypeptides chains are present in a multimedia protein?

Answer 1

Hint: Some naturally occurring proteins have a moderately small number of subunits and hence are described as oligomeric for example, hemoglobin or DNA polymerase. Proteins that consist of a very vast number of subunits and are accordingly described as multimeric for example, microtubules and additional cytoskeleton proteins.

Complete answer:
A protein complex or multiprotein complex is an organization of two or more associated polypeptide chains. Varied polypeptide chains may have different functions. This is different from a multienzyme complex, in which multiple catalytic domains are found in a single polypeptide chain. Protein complexes are a pattern of quaternary structure. Proteins in a protein complex are associated by non-covalent protein-protein interactions, and other protein complexes have different degrees of equilibrium over time.

Multimeric proteins arrangement
A. Protein subunits are held together primarily by hydrophobic interactions, but also by salt bridges and H-bonds.
B. Contacting surfaces are companions - hydrophobic patches will be aligned with hydrophobic patches which means the H-bond donor will align with the H-bond acceptor in simple words the positive charge attracts a negative charge.
C. Structures enclosing similar subunits will have all subunits in corresponding positions.
Types of multimedia proteins-
> Homomeric
> Heteromeric
> Homomeric, heteromeric and multimeric denominations refer to proteins quaternary structure.

Quaternary structure is the global structure of protein complexes formed by two or more subunits. And then each subunit is a protein and they interact with each other through weak molecular interactions.

A protein complex is homomeric when all its subunits consist of the identical protein. Whereas heteromeric complexes are prepared of different protein subunits and for this multimeric complexes are made of several subunits.

Note: Proteins may constitute a very large number of subunits and then described as multimeric, for example- microtubules and other cytoskeleton proteins. The subunits of protein may be similar, homologous, or different and attached to disparate duties.