BIO304H5 Lecture Notes - Lecture 6: Nicotinic Acetylcholine Receptor, Alpha Helix, Disulfide
Document Summary
Pumps + exchangers keep ion gradients stable gradients establish rmp and allow excitability. Ion channels create pore in the membrane allowing for changes in membrane voltage with aps and graded potentials. Na channels depolarize cell, k channels hyperpolarize cell, ca channels depolarize cell, cl channels depolarize or hyperpolarize depending on the gradient. At certain voltages, ions will flow against gradients nach receptors at neuromuscular synapses in both vertebrate + invertebrate. It"s a ligand gated ion channel each subunit of the receptor has a cy-loop (cysteine + 13 amino acids. The 2 cysteines form a disulfide bond and this forms the cys loop. When ach binds to the alpha subunit of ach receptor, it induces a conformational change which increases its affinity for more ach. These open when bound to ach and bring in na which depolarizes muscle cells this activates ca channels to start muscle contraction. Molecular techniques for characterizing ion channels + receptors: biochemically isolate + identify channel protein.
