Part 1 Flashcards
(10 cards)
What are the different modes of cell signaling? How is each types of signaling carried out by the cell?
Cell to cell: signaling results from either direct contact of a cell with its neighbor. Critical role regulating behavior of cells in animal tissue, and different types of cells during embryonic development.
Action of secreted signaling molecules:
Endocrine: Signaling molecules are secreted by specialized endocrine cells and carried through the circulation to act on target cells at distant body sites.
Paracrine: Act locally to affect the behavior of nearby cells. The molecule is released by one cell and acts on neighboring target cells.
Autocrine: Some cells respond to signaling molecules they themself have produced. Receptors on the surface of the cell.
What characteristics of steroid hormones enable them to carry out their mode of signaling?
They are hydrophobic they are able to enter cells by diffusing across the plasma membrane is facilitated by carrier proteins. Once inside the cell able to bind to intracellular receptors that are expressed by hormonally responsive target cells.
What are the major steps in glucocorticoid signaling?
1) Glucocorticoud diffuse across plasma membrane into cytoplasma
2) Glucocorticoud binds to inactive Glucocorticoud receptor/chaperone complex
3) Confirmation change on the receptor causes Hsp90 to be dispalced
4) Nuclear localization signal is exposed and the dimer is transported across the nuclear envelope
6) Receptors dimer binds to the recogonition sites in DNA
7) Association with co activators with histone acetlytrnasferase activity to stimulate transcription
How are genes under the control of the thyroid hormone receptor regulated? What role does HDAC and HAT have in switching these genes on and off?
In the absence of hormone: Receptor associates with co repressors with histone deacetylase activity (HDAC). Results in the repression of the target gene expression
Hormone present: Hormone binds to receptor. Induces conformational change. Co repressor displaced. Association with cofactors with histone acetyltransferase (HAT) activity.
How does nitroglycerine work in the treatment of heart disease?
NO alters the activity of the intracellular target enzyme guanylyl cyclase, stimulates synthesis of cyclic GMP inside the cell.
Nitroglycerin is a source of NO it allows for the rest of the pathway to happen which in the end results in muscle relaxation. Converted to NO which dilated blood vessel and increases blood flow to heart.
What are the main groups of peptides signaling molecule?
Peptide Hormones: include insulin and hormones produced by pituitary gland
Neuropeptides: include enkephalins, endorphins
Growth factors: Wide variety of signaling molecules that control animal cell growth and differentiation
What is the basic structural unit of a peptide signaling molecule?
A chain of amino acids linked by peptide bonds.
Do peptide signaling molecules act at the surface of the cell or do they cross the plasma membrane?
They act on the surface of the cell. Polypeptides unable to cross plasma membrane so they act by binding to cell surface receptors
What are the structural characteristics of G protein coupled receptors?
Carbohydrates are required for proper folding of receptor. Extracellular binding domain. G coupled receptors have seven transmembrane alpha helices panning across the cell membrane. Intracellular ligand binding domain has guanine nucleotide exchange factor activity.
G protein coupled receptors typically have carbohydrate groups attached to the extracellular portion of the protein. What might be the role of those carbohydrates?
required for proper folding of receptor, stability, and trafficking to the membrane. They can influence ligan binding, protect the receptor from degradation and facilitate cell to cell recognition. Ensure effective receptor signaling in cellular environment.
