MHC class I molecules include which of the following proteins?

MHC class I molecules are integral to the immune system, particularly in presenting intracellular antigens to CD8+ cytotoxic T cells. The proteins that comprise MHC class I molecules include specific heavy chain proteins, which are well-characterized as HLA A, B, and C. These proteins are encoded by the human leukocyte antigen (HLA) complex and play a crucial role in the recognition of foreign peptides by T cells.

The presence of beta-2 microglobulin is important as it associates with the heavy chain of MHC class I molecules, but it is not considered a part of the heavy chain itself. Instead, it serves as a stabilizing component for the overall structure of the MHC class I molecule.

Other choices listed, such as HLA DQ, DR, and DP, are representatives of MHC class II molecules, which are involved in presenting antigens to CD4+ T helper cells. Complement proteins do not participate in MHC function or structure. This distinction is vital for understanding the function and classification of these immunological proteins.