Receptors and Intracellular Signaling II

Flashcards summarizing key concepts from the lecture on receptors and intracellular signaling mechanisms.

What is the overall objective of the lecture on receptors and signaling mechanisms?

To review how hormones alter the activity of target cells and produce physiological actions.

What are ionotropic receptors?

Ligand-gated ion channels that open upon ligand binding, allowing cations like Na+ or Ca2+ to enter the target cell.

What is an example of a paracrine ionotropic receptor?

Nicotinic acetylcholine receptor acting on adrenal chromaffin cells.

What do catalytic receptors result in upon ligand binding?

Dimerization of two receptors to form a functional unit and activation of an intracellular catalytic domain.

What is the function of guanylyl cyclases?

They convert GTP to cyclic GMP (cGMP), which activates downstream messengers.

What are receptor tyrosine kinases?

Catalytic receptors that, upon activation by ligand binding, become dimerized and phosphorylate tyrosine residues.

What is the role of the insulin receptor after ligand binding?

It changes conformation, leading to the autophosphorylation of its intrinsic tyrosine kinase.

What defines tyrosine kinase-associated receptors?

They activate associated tyrosine kinases like JAK or Src after ligand binding and do not have intrinsic kinase activity themselves.

What happens to steroid hormones once they enter target cells?

They bind to intracellular receptors that act as transcription factors, leading to gene transcription.

How do glucocorticoid receptors (GR) work in terms of transcription?

When cortisol binds to GR, it dissociates from hsp90, translocates to the nucleus, and initiates transcription.

What impact can hormone/receptor interactions have on cell function?

They can alter target cell function via mechanisms like ion channel opening or transcriptional activation/repression.

What is pseudohypoparathyroidism?

A condition where the PTH receptor signaling is defective, causing hypocalcemia due to inability to regulate calcium levels.

What are the implications of defective receptor/signaling mechanisms in diseases?

They are often associated with various diseases, making research and therapeutic development targeting these mechanisms crucial.