BI459 Lecture Notes - Lecture 3: Aldehyde Oxidase, Golgi Apparatus, Thyroid
Document Summary
Four main groups based on chemical nature: peptides and proteins (water soluble, amino-acid derivatives (water soluble) Single amino acids: steroids (lipid soluble, fatty acid derivatives eicosanoids (lipid soluble) In general: water-soluble hormones have cell surface receptors, lipid-soluble hormones have intracellular receptors. Synthesized in the er: needs to have pre-er signal. They vary considerably in size (3-100s of amino acids) and post-translational modifications. Different types: proteolytic, chemical: release of inactive (pro) segment , mature form released from large precursor by multiple proteolytic cleavages. Post-translational processing may occur within: rough er, golgi apparatus, storage granules. Er (synthesis) golgi secretory granules (for secretion) Regulated secretion: granules stored and released upon cell stimulation: most common; allows cells to secrete large amounts of hormones in little time. Constitutive secretion hormones in secretory vesicles are secreted as it is synthesized. Two groups of hormones derived from tyrosine: thyroid hormones: double tyrosine with incorporation of 3 or 4 iodine atoms, catecholamines (catechol ring structures: epinephrine, norepinephrine, dopamine)
