Question

Signal transduction pathways are central to the regulation of cellular processes. Which of the following statements is not true of signal transduction pathways?

Group of answer choices

Signal transduction pathways typically involve the activation of protein kinases and protein phosphatases.

When a hormone binds to a G-protein-coupled receptor, a conformational change in the receptor activates the associated GTP-binding protein.

Intracelluar second messenger molecules include cGMP, calcium ions and inositol trisphosphate.

A receptor protein has an extracellular domain that is responsible for interacting with a specific ligand such as a hormone.

7-transmembrane segment (7-TMS) receptors typically have a tyrosine kinase activity.

Answer 1

The correct answer is option 5 - 7-transmembrane segment (7-TMS) receptors typically have a tyrosine kinase activity.

Explanation: This statement is not true. G protein coupled receptor has 7 transmembrane segments and they activates G protein mediated signal transduction. They don't have tyrosine kinase activity. They remain bound to G protein with bound ADP. when ligand bind to them, GDP is replaced by GTP, and GTP alpha subunit dissociates from the GPCR and activates second messenger.