Concept explainers
(a)
Interpretation:
The function of Csk as tumor-suppressor gene or a proto-oncogene is to be determined.
Concept introduction:
Tumor suppressor genes that are responsible for regulating cell growth and division, repair DNA, and regulates apoptosis. Any mutation in the tumor suppressor gene can lead to uncontrolled cell division, ultimately resulting in cancer. Any normal gene upon mutation leading to a cause of cancer is termed as the proto-oncogene. The proto-oncogene upon permanent activation leads to cancer, while tumor suppressor gene upon inactivation causes cancer.
(b)
Interpretation:
The function of PTP1B as tumor-suppressor gene or a proto-oncogene is to be determined.
Concept introduction:
Tumor suppressor genes that are responsible for regulating cell growth and division, repair DNA, and regulates apoptosis. Any mutation in the tumor suppressor gene can lead to uncontrolled cell division, ultimately resulting in cancer. Any normal gene upon mutation leading to a cause of cancer is termed as the proto-oncogene. The proto-oncogene upon permanent activation leads to cancer, while tumor suppressor gene upon inactivation causes cancer.
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BIOCHEMISTRY W/1 TERM ACHEIVE ACCESS
- Some strains of bacteria or microorganisms have developed toxins that can modify the activity of the alpha subunit of G proteins which results in disease. For ex. cholera toxin, produced by Vibrio cholerae, causes ADP ribosylation of the stimulatory Gαs subunit of G proteins. This modification abolishes the GTPase of Gαs, and results in an αs subunit that is always in the “on” or active state. It results in continuous stimulation of adenylyl cyclase (AC). The main cells affected by this are the epithelial cell in gastrointestinal tract. Knowing this altered activity of AC, explain why patients affected by this toxin experience severe diarrhea and dehydration that may result in death.arrow_forwardSome protein kinases are inactive unless they are phosphorylated on key serine or threonine residues. In some cases, active enzymes can be generated by mutating these serine or threonine residues to aspartate. Explain.arrow_forwardIn the case of GPCR (G protein coupled receptor) signaling pathways, which of the following statements is INCORRECT? The gamma subunit of the trimeric G protein has a transmembrane domain whereas the alpha and beta subunits are peripheral proteins If G alpha was locked in a GTP bound state, it would be bound to the effector enzyme rather than to the beta and gamma subunits. In some but not all signaling pathways, when the beta and gamma subunits are separated from alpha - the beta/gamma pair can also stimulate the activation of effectorsarrow_forward
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- In Figure 4C, we see the inhibition of LRRK2 kinase activity by nanobody 1 (Nb1). Using the Lineweaver-Burke plot, estimate the Km of LRRK2 in the absence of Nb1. Show your work and provide your answer with the correct units.arrow_forwardSome protein kinases are inactive unless they are phosphorylated on key serine or threonine residues. In some cases, active enzymes can be generated by mutating these serine or threonine residues to glutamate. Explain. What could you predict about a mutant generated replacing the serine or threonine with alanine.arrow_forwardProtein Kinase A can phosphorylate different proteins in different cells. Explain the role of AKAP’s (A Kinase Anchoring Protein’s) in determining which substrates of Protein Kinase A will get phosphorylated in particular cells.arrow_forward
- Many enzymes can hydrolyze GTP between the β and γ phosphates. The GTP analog β,γ-imidoguanosine 5′-triphosphate (Gpp(NH)p), shown below, cannot be hydrolyzed between the β and γ phosphates. Predict the effect of microinjection of Gpp(NH)p into a myocyte on the cell’s response to β-adrenergic stimulation.arrow_forwardReceptor tyrosine kinases such as the epidermal growth factor (EGF) receptor can basically be broken down into three domains: (1) An extracellular, ligand binding domain, (2) A transmembrane domain that must cross through the cell membrane, and (3) an intracellular domain. Match the amino acid with the domain that it would MOST LIKELY be associated with. Lysine (choose (1), (2), or (3) from above) A tyrosine residue capable of being phosphorylated on its hydroxyl group (choose (1), (2), or (3) from above) Isoleucine (choose (1), (2), or (3) from above)arrow_forwardThe Luteinizing hormone receptor (LHR) is a GPCR that predominantly couples to Gαs (G alpha s) G proteins in response to binding of the endogenous ligand luteinizing hormone (LH). Briefly describe how activation of this receptor ultimately leads to protein kinase A (PKA) activation.arrow_forward
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