Question

Which of the components of the MAP kinase pathway mediates changes in gene transcription:

A. MAP kinase (Erk)
B. MAP kinase kinase kinase
C. Ras protein
D. MAP kinase kinase (Mek)

Answer 1

The component of the MAP kinase pathway that mediates gene transcription changes is the MAP kinase (Erk). It phosphorylates transcription factors in the nucleus, affecting gene activity, cell proliferation, and differentiation.

Step-by-step explanation:

The component of the MAP kinase pathway that mediates changes in gene transcription is A. MAP kinase (Erk). The pathway involves a phosphorylation cascade wherein MAP kinase kinase kinase (MAPKKK) phosphorylates MAP kinase kinase (MEK), which, in turn, phosphorylates ERK, a MAP kinase.

The phosphorylated ERK then enters the nucleus, where it triggers a cellular response by phosphorylating transcription factors and other nuclear proteins that affect gene activity, leading to cell proliferation and differentiation.

This process is vital for various cellular processes including cell division and differentiation, and abnormal MAP kinase signaling is associated with diseases such as cancer. For example, the ERK phosphorylates MNK1, which then phosphorylates elF-4E, an initiation factor associated with mRNA, initiating protein synthesis.

Overall, the MAP kinase pathway is critical for protein expression, cellular metabolism, and cell division, influencing cellular functions as a result of external stimuli like epinephrine and EGF (epidermal growth factor).