23. Iasulin, a homo that is secreted in ponse to high blood sugar levels is a pr

Question

23. Iasulin, a homo that is secreted in ponse to high blood sugar levels is a protein that has following ne targeting sequence(s) Th 24 its peculiar shape, or scientifically speaking 3D stmucture, to two post-translational modifications. 25 These post-translational modifications take place in the and respectively 26 Improperly folded insulin molecules that are result ofmistakes in translation are destroyed in the large complexes of proteases localized in the cytosoi 27 To be recognized and allowed entry to the doomed proteins undergo a process of attachment of a small cytosolic protein Insulin binds to a 29 When activated, insulin receptor interacts with IRS l and grb2 and sos proteins that operate via direct protein-protein contact. 30. As a result of the cascade of signaling events oba won tie pe the final effect of insulin in muscle cells and increased glucose transport into the cells lasulin has more playsiological effects than just glucose transport. In a "big picture, the physiological roles of insulin are 3, and to preserve any santry and good anoodpioase do mor menuto low ag of blood ghacosolovels 32. 35. If these cells are destroyed by autoimmaunereactions or total resection of pancreas the disease that ensues is diabetes mellitus This disease has been known for many, many years and one of the called visible symptoms was sweet urine. 36. The presence of glucose in urine is the result of the transporter protein that is responsible for glucose reabsorption in the kidneys. This transporter protein. has the saturation threshold of about IS0 ng ml. Now am sure I have stressed you enough and your adrenaline (epinephrine) is running high. So of course next questions are about stress General Adaptation Svmdrome (GAS)is divided into 3 specific phases 40. The first phase of GAS is the effect of hormone 11. There are two types of adrenergic receptors, alpha and beta. Both ofthem are When epineplaine binds to the adrenergic receptors it causes many changes in the body. One of effects is the increase of blood glucose levels. List 2 more effects of epinephi in the body ime Now let's talk about signaling cascade initiated by beta adrenergie receptors in the liver and muscles 44. Adrenergic receptors activate G proteins as the first step of signaling. Gproteins are called molecular switches. What is the mechanism of activation of G proteins by receptors? 45. The second step in epinephrine signaling is the production of second messengers, What enzyme makes cAMP from ATP? 46. CAMP bindsto and activates protein kinaie A (PKA). In tum PKA glycogen phosphorylase kinase (GPK)

Explanation / Answer

23. N-terminal ER targeting sequence
24. a) Formation of disulphide bond between A and B chain b) removal of intervening C chain
25. a) Endoplasmic reticulum b) Golgi complex.
After translation of insulin from its mRNA, preproinsulin carries a signal peptide on the N terminal which directs it to be transported to rough endoplasmic reticulum. Here it is cleaved to form proinsulin. Proinsulin is then transported to golgi complex where it is again cleaved to form insulin and C-peptide.
26. Endoplasmic reticulum
27. Golgi complex , glycosylation
28. Insulin receptor tyrosine kinase
29. Activation of Ras pathway
30. Glucose uptake in muscle
Physiological roles of insulin :
31. Increased- DNA replication and lipid synthesis, esterification, potassium uptake, glycogen synthesis, amino acid uptake and HCL production.
32. Decrease in renal sodium excretion
33. Control over glucose uptake into muscles and adipose tissue.
34. Increased glycogen synthesis and decreased gluconeogenesis.
35. Type 2
36. inhibition , Sodium-glucose cotransporter 2
37. Alarm stage,
38. Resistance stage
39. Exhaustion stage
40. Adrenaline
41. G protein coupled receptors.
42. Relaxation of smooth muscles.
43. Increase in contraction rate of heart
44. G protein coupled receptors act as guanine nucleotide exchange factors for the alpha subunit of the G protein. When the receptor is activated, it promotes exchange of GDP for GTP on alpha subunit. When GTP binds to alpha subunit, there is a molecular switch mechanism within alpha subunit which then results in release of GTP from receptor. It further leads to a cascade activating different effectors and ion channels. These effectors further regulate intracellular concentrations os secondary messengers cAMP,cGMP,IP3 etc.
45. Adenylate cyclise
46. Phosphorylates

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