Which of the following is a common characteristic of γ-globulins?

γ-globulins are primarily composed of immunoglobulins, making this choice the most accurate representation of their characteristics. Immunoglobulins are essential components of the immune system, functioning as antibodies that help identify and neutralize pathogens like bacteria and viruses. The presence of these immunoglobulins is what predominantly defines the nature of γ-globulins, distinguishing them from other protein fractions.

The other characteristics listed do not adequately describe γ-globulins. For instance, γ-globulins are not the fastest migrating proteins; that distinction often belongs to albumin. Furthermore, they do not have the highest molecular weight compared to other protein fractions. Additionally, γ-globulins are typically characterized by a higher pI (isoelectric point) relative to other proteins, not low pI. Thus, the characterization of γ-globulins as predominantly immunoglobulins is fundamental to understanding their function and significance in clinical chemistry and immunology.