Question

Which one of the following statements is not true regarding receptors?

A. Seven-transmembrane-domain receptors require G proteins to open ion channels
B. In the ligand-gated ion channel receptor, the channel is built into the complex that binds the ligand
C. Seven-transmembrane-domain receptors have an external NH2 terminal end and an intracellular COOH terminal end
D. Nerve growth factor (NGF) and brain-derived neurotropic factor (BDNF) bind to seven-transmembrane domain receptors
E. Hormones may diffuse into the cell and bind cytoplasmic receptors, which leads to influence over gene expression

Answer 1

The incorrect statement is D. NGF and BDNF do not bind to seven-transmembrane domain receptors but to receptor tyrosine kinases. Other statements regarding the function and structure of different types of receptors are correct.

Step-by-step explanation:

Among the choices provided, the statement that is not true regarding receptors is D. Nerve growth factor (NGF) and brain-derived neurotropic factor (BDNF) bind to seven-transmembrane domain receptors. NGF and BDNF actually bind to receptor tyrosine kinases, which are a type of enzyme-linked receptor, not to the G-protein-linked receptors that have seven transmembrane domains.

The other statements are true: A. Seven-transmembrane-domain receptors indeed require G proteins to open ion channels; B. In the ligand-gated ion channel receptor, the channel is part of the complex binding the ligand; C. Seven-transmembrane-domain receptors have an external NH2 terminal end and an intracellular COOH terminal end; and E. Hormones may diffuse into the cell and bind to cytoplasmic receptors, influencing gene expression.