Which of the Sequences Below Best Describes the Sequential Steps

Multiple Choice

Which of the sequences below best describes the sequential steps (numbered 1-5) in a signal transduction pathway that utilizes a G protein-coupled receptor?
1) The signal-receptor complex activates a G protein.
2) Protein kinases are activated.
3) A signal molecule binds to a receptor.
4) Target proteins are phosphorylated.
5) cAMP is produced.

A) 1, 2, 3, 4, 5
B) 3, 1, 2, 4, 5
C) 3, 1, 5, 2, 4
D) 1, 2, 5, 3, 4