Final answer:
Ras protein is anchored in the cell membrane through prenylation, which attaches lipid groups to its C-terminus allowing membrane association. This process is crucial for the Ras-mediated MAP kinase signaling pathway linked with cellular processes such as cell division, protein expression, and metabolism. Mutations in Ras protein's GTPase activity are common in cancers.
Step-by-step explanation:
The question pertains to how the Ras protein is anchored in the cell membrane. The correct answer is B. Prenylation. Ras protein does not have a transmembrane domain; instead, it is anchored in the cell membrane through the process of prenylation. Prenylation is a post-translational modification that involves the attachment of lipid groups to the C-terminus of the protein, which allows for membrane association. Unlike proteins with transmembrane domains that span the membrane, prenylated proteins are tethered to the cytosolic face of the membrane.
This anchorage is critical for its role in signal transduction, particularly for the Ras-mediated MAP kinase signal transduction pathway that is involved in cellular processes like cell division, protein expression, and metabolism. Mutations in the Ras protein, in the context of its GTPase activity, are known to be common in cancers, reflecting the protein's significant role in controlling cell proliferation.