BIOL 460 1nd Edition Lecture 7 Outline of Last Lecture I Reflex II Endocrine System Chapter 11 a Endocrine b Exocrine III Hormone classification i Chemically ii Solubility Outline of Current Lecture I Mechanisms of Hormone action a Lipophilic b Steroid hormone family c Thyroid hormone family II Glands Current Lecture Mechanisms of hormone action 1 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 domains These 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 2 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 process 1 Carrier protein hormone bond is transitory strong but occasionally break 2 Receptors found in cytoplasm of target cell 3 Need t2 NRP and 2 molecules of hormones to bond to both halfsites 4 After both bind they dimerize 5 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 coactivatorsregulatory proteins e 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 T4 iii Transported by thyroxin binding globulin T4 binds more readily more free T3 in blood iv 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 element viii 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 Polar Hormones a Receptors on plasma membrane b React through STPs c STPs alter activity of already present enzymes and proteins d Three systems i Andenylate cyclase cAMP 2nd messenger system 1 Epinephrine norepinephrine 2 Beta adrenergic receptors ii Phospholipase C C2 2nd messenger system 1 Alpha 1 adrenergic receptors iii Tyrosine kinase 2nd messenger system 1 Ligands are generally growth factors or insulin similar effects to GF 2 Ligands are usually growth factors 3 This stimulate cell reproduction 4 Growth factors are evolutionarily ancient a Gene tinman b Causes heart formation in fruit flies and chordates 5 Families of growth factors a Fibroblast growth factor b Bone morphogenetic protein c Neurotropins 6 Before growth factor two inactive monomers in PM FIG 11 11 a Ligand binding domain in extracellular space b Catalytic enzymatic domain catalyzes reaction c Growth factor binds two monomer dimerize d Auto phosphorylation occurs e Amino acid residues f Tyrosine kinase phosphorylates tyrosine residues g Monomer 2 phosphorylates monomer 1 and vice versa h Turns receptor on i 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 Glands 1 Pituitary gland hypophysis below growth a Growth beneath hypothalamus of diencephalon b On stalk called infundibulum c Anterior lobe adenohypophysis d Posterior lobe neurohypophysis
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