An IgG2 molecule is composed of which of the following?

IgG molecules contain two gamma heavy chains of a given subtype and two light chains (either kappa or lambda). The 2 in IgG2 indicates the subclass to which the molecule belongs. IgG2 contains two gamma2 chains (since a given B cell can only form one type of heavy chain). The IgG molecule will contain either two kappa chains or two lambda chains, but never one of each. A given cell produces immunoglobulin molecules with a single type of heavy chain. IgG molecules with gamma1 chains would be of the IgG1 subclass. Ref: Levinson W. (2012). Chapter 58. Cellular Basis of the Immune Response. In W. Levinson (Ed), Review of Medical Microbiology & Immunology, 12e.