Question

What is the composition of major histocompatibility class (MHC) I molecules?

a) Two alpha chains
b) Two beta chains
c) One alpha chain and one beta chain
d) One alpha chain and one gamma chain

Answer 1

MHC Class I molecules are composed of one alpha chain and one beta chain, the latter being beta2-microglobulin. Both the alpha chain and beta2-microglobulin are necessary for the formation of a functional MHC Class I molecule.

Step-by-step explanation:

MHC Class I molecules are essential components of the immune system that consist of a heavy chain referred to as the alpha chain and a smaller chain known as β2-microglobulin. The alpha chain of MHC I is divided into three domains - α1, α2, and α3, with the α chain being a transmembrane protein that spans the cytoplasmic membrane. In contrast, MHC Class II molecules are made up of two similarly sized chains, an alpha and a beta chain. To answer the multiple-choice question, MHC Class I molecules are composed of one alpha chain and one beta chain, which is specifically β2-microglobulin. This comes from option c) One alpha chain and one beta chain.