Kinases

Question 1

What are kinases?

Answer 1

Kinases are enzymes that transfer phosphate groups from ATP to specific substrates, playing a crucial role in cellular signaling.

Question 2

How are kinases activated?

Answer 2

Kinases are often activated through phosphorylation of the activation loop or by binding regulatory proteins, altering their structure to activate them.

Question 3

How do kinases recognize specific substrates?

Answer 3

How do kinases recognize specific substrates?

Question 3

What are the main types of kinases?

Answer 3

Kinases are classified into serine/threonine kinases and tyrosine kinases based on the amino acids they phosphorylate.

Question 4

What families do kinases belong to?

Answer 4

Kinase families include the AGC, CAMK, and CMGC families, which group kinases with similar structures and functions.

Question 4

What mechanisms regulate kinases?

Answer 4

Kinases are regulated by phosphorylation, binding of regulatory proteins, and cellular localization.

Question 5

How is structural biology used in studying kinases?

Answer 5

Techniques such as X-ray crystallography and NMR spectroscopy are used to study kinase structures.

Question 5

What is a kinase assay?

Answer 5

Kinase assays measure kinase activity and screen for inhibitors using techniques like radioactive, fluorescent, and mass spectrometry-based assays.

Question 6

What are kinase inhibitors and their use?

Answer 6

Kinase inhibitors block kinase activity and are used as therapeutic agents in diseases like cancer.

Question 7

What roles do kinases play in diseases?

Answer 7

Kinases are implicated in diseases like diabetes and neurodegenerative diseases, and mutations in kinases can lead to various diseases.

Question 8

What is allosteric regulation of kinases?

Answer 8

Allosteric regulation involves molecules binding at sites other than the active site to modulate kinase activity.

Question 9

How are PKCs classified?

Answer 9

PKCs are classified into classic (require calcium), novel (activated by DAG), and atypical (do not require calcium or DAG) groups.

Question 9

What is Protein Kinase C (PKC)?

Answer 9

PKC is a family of enzymes that phosphorylate serine and threonine residues on target proteins, playing critical roles in several cellular processes.

Question 10

How are PKCs activated?

Answer 10

PKCs are activated by binding specific cofactors that induce conformational changes, relieving autoinhibition by the regulatory domain.

Question 10

What is the role of the pseudosubstrate segment in PKCs?

Answer 10

The pseudosubstrate segment keeps PKCs inactive by blocking the catalytic site, mimicking the actual substrate without being phosphorylated.

Question 11

What domains do PKCs have?

Answer 11

PKCs have an N-terminal regulatory domain and a C-terminal catalytic domain.

Question 12

How does Protein Kinase A (PKA) get activated?

Answer 12

PKA is activated by cAMP binding to its regulatory subunits, releasing and activating the catalytic subunits.

Question 13

How does muscle contraction affect phosphorylase kinase?

Answer 13

Muscle contraction increases Ca²⁺ levels, directly activating phosphorylase kinase, which then activates glycogen phosphorylase to break down glycogen for energy.

Question 14

What is the structure of Src kinases?

Answer 14

Src kinases have SH3, SH2, and kinase domains, along with a regulatory tail that controls their activity.

Question 15

How are Src kinases activated?

Answer 15

Src kinases are activated by dephosphorylation of Tyr527 and binding of SH2 and SH3 domains to target proteins, inducing conformational changes.

Question 16

What functions do Src kinases have?

Answer 16

Src kinases regulate cell growth, survival, adhesion, migration, differentiation, and immune responses.

Question 17

What are tyrosine kinase inhibitors and their role in CML?

Answer 17

Tyrosine kinase inhibitors, like Gleevec, target abnormal kinase activity in CML by blocking the ATP-binding site of the BCR-ABL fusion protein.

Question 18

What types of signal transduction exist?

Answer 18

Signal transduction can be intercellular (communication between cells) or intracellular (signal processing within a cell).

Question 19

What mechanisms regulate gene expression?

Answer 19

Gene expression is regulated through protein-DNA interactions, transcription regulation, and posttranscriptional processes.

Question 19

How is enzymatic activity regulated?

Answer 19

Enzymatic activity is regulated by allosteric regulation, inhibitors/activators, phosphorylation, and proteolysis.

Question 20

What is the role of PKC in the inositol phosphate cycle?

Answer 20

PKC is activated by DAG in the inositol phosphate cycle, leading to downstream signaling events and feedback regulation of enzymes like PLC.

Question 21

What is the role of PKA in glycogen metabolism?

Answer 21

PKA phosphorylates phosphorylase kinase, making it more active and ensuring efficient glycogen breakdown during muscle contraction.

Question 22

How does cAMP regulate PKA?

Answer 22

cAMP binds to PKA’s regulatory subunits, causing a conformational change that activates the catalytic subunits.

Question 23

What is the function of the SH2 domain in Src kinases?

Answer 23

The SH2 domain binds to phosphorylated tyrosine residues, playing a critical role in signal transduction.