BIOL 460 1nd Edition Lecture 7Outline of Last Lecture I. Reflex II. Endocrine System (Chapter 11)a. Endocrine b. Exocrine III. Hormone classification i. Chemicallyii. Solubility Outline of Current Lecture I. Mechanisms of Hormone actiona. Lipophilic b. Steroid hormone familyc. Thyroid hormone family II. Glands Current LectureMechanisms of hormone action1. Lipophilic hormones a. Intracellular receptors b. Genomic action i. Causes genes to be turned on c. Results in new proteins- often enzymes d. Steroids hormones/thyroid hormones i. Transported in blood by carriers ii. Nuclear receptor proteins 1. Act as transcription factors 2. Molecules that bond to promoter DNA sequence 3. Have two domainsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.a. Ligand binding b. DNA binding iii. Hormone response element 1. Composed of two half-sites 2. Each 6 base pairs (bp) in length 3. 3 bp gap in between 4. NRP binds to half site iv. Steroid hormone family process1. Carrier protein/hormone bond is transitory- strong, but occasionally break2. Receptors found in cytoplasm of target cell3. Need t2 NRP and 2 molecules of hormones to bond to both half-sites 4. After both bind they dimerize5. Dimerizing usually turns on transcription 6. Genomic action of steroid 7. Same NHR and same hormones turn on different genes in different types of cells 8. Transcription also involves corepressors and coactivators- regulatory proteinse. Thyroid Hormones ( thyroid hormone family)i. Synthesized from tyrosine (two forms)1. T3- 3 iodine atoms, triiodothyronine 2. T4- 4 iodine atoms, thyroxin (first discovered)ii. Thyroid gland produced both, but more T4iii. Transported by thyroxin binding globulin, T4 binds more readily, more free T3 in bloodiv. T4 converted to T3 in target cell v. T3→ nucleus vi. Nuclear receptor proteins already in nucleus vii. Already bound to half-sites of hormone-response elementviii. Receptors are bound to corepressors without hormone ( preventing genomic action)ix. T3 bind to TR (thyroid hormone receptor)9-cis retinoic acid bind to RXR both binding causes heterodimerization and gene expression x. Corepressors done away with, coactivators come in and promote transcription 2. Polar Hormonesa. Receptors on plasma membrane b. React through STPs c. STPs alter activity of already present enzymes and proteinsd. Three systems i. Andenylate cyclase/cAMP 2nd messenger system1. Epinephrine/ norepinephrine2. Beta adrenergic receptorsii. Phospholipase C/C2+ 2nd messenger system 1. Alpha 1 adrenergic receptorsiii. Tyrosine kinase 2nd messenger system 1. Ligands are generally growth factors or insulin (similar effects to GF)2. Ligands are usually growth factors3. This stimulate cell reproduction4. Growth factors are evolutionarily ancient a. Gene- tinmanb. Causes heart formation in fruit flies and chordates5. Families of growth factorsa. Fibroblast growth factorb. Bone morphogenetic protein c. Neurotropins 6. Before growth factor- two inactive monomers in PM ( FIG 11.11)a. Ligand binding domain in extracellular spaceb. Catalytic/enzymatic domain catalyzes reaction c. Growth factor binds, two monomer dimerized. Auto phosphorylation occurs e. Amino acid=residuesf. Tyrosine kinase phosphorylates tyrosine residues g. Monomer 2 phosphorylates monomer 1, and vice versa h. Turns receptor oni. Catalytic portion of receptor phosphorylates tyrosine residues of signaling molecules (this time using P from ATP)j. Can phosphorylate tyrosine residues of 10 signaling molecules at a time Glands1. Pituitary gland/hypophysis (below growth)a. Growth beneath hypothalamus of diencephalon b. On stalk called infundibulumc. Anterior lobe- adenohypophysis d. Posterior lobe-
View Full Document
Unlocking...