CPPS 325 FINAL EXAM QUESTIONS AND VERIFIED
CORRECT ANSWERS 2025-2026 || 100% GUARANTEED
PASS <BRAND NEW VERSION>
What is the reciprocal of RTK? - CORRECT ANSWER- Receptor Tyrosine Phosphatases. They
take the phosphate off the tyrosine residues to inactivate signalling cascades.
Ex. Transforming GF Beta superfamily of receptors, cell type dependent.
What is the major mechanism for receptor signal transduction? - CORRECT ANSWER- Tyrosine
kinase phosphorylation
RTK vs. Serine/Threonine Phosphorylation ? - CORRECT ANSWER- Tyrosine phosphorylation is
rare (1%) relative to serine/threonine residue phosphorylation. Tyrosine phosphorylation is the
major mechanism of receptor signal transduction.
What is the net effect of activated TKs? - CORRECT ANSWER- Tyrosine phosphorylation on
target proteins.
What do TK pathways mediate? - CORRECT ANSWER- Cell growth (growth factors),
differentiation, host defense, metabolic regulation, cell survival pathways (survival factors).
What are amplifiers of the TK pathways? - CORRECT ANSWER- PI3-K -> PIP3
PLC -> DAG and InsP3&Ca2+
,What are the 5 well-known enzyme-linked cell surface receptors? - CORRECT ANSWER- 1.
Receptor Guanylyl Cyclase: produces cGMP
2. RTK: phosphorylate tyrosine residues leading to association of signalling molecules and
cascade
3. TK Associated Receptors: associate with proteins having TK activity
4. Receptor Tyrosine Phosphates: Removes phosphate on tyrosine residues
5. Receptor Serine/Threonine Kinases: phosphorylate specific Serine/Threonine residues on IC
signalling molecules
How are RTK and TK Associated Receptors different? - CORRECT ANSWER- RTK phosphorylate
tyrosine while associated receptors bind/find proteins with TK activity to initiate the cascade of
signalling.
What are RTK mediated actions in the cell? - CORRECT ANSWER- regulation of cell
proliferation, differentiation, and cell motility, promotion of cell survival and modulation of
cellular metabolism.
TKs exist in either the cytosol or as transmembrane receptors, what are the differences in the
two types? - CORRECT ANSWER- Cytosol receptors have an src N-terminal region. Cytosol has
no membrane spanning domain.
TM receptor has a single membrane spanning hydrophobic TM domain. Ex) Epidermal GF RTK.
What is src? - CORRECT ANSWER- Src is a non-receptor TK, so it does not span a membrane. It
is a tyrosine kinase. And although it is cytoplasmic TK it can still bind to activated RTKs.
What is contact inhibition confluency? - CORRECT ANSWER- Stops Src domains signalling and
therefore cells stop dividing.
, If there is an issue then cancer can result and mutation causes an inhibition of the stop signal so
the cells keep growing and dividing.
What are SH domains? - CORRECT ANSWER- Src homology domains. Src and other proteins
that have src-homology domains can bing to activated RTKs.
What are the different SH domains in proteins? - CORRECT ANSWER- There are SH1, SH2 and
SH3 domains.
What isSH1 domain characterized by? - CORRECT ANSWER- Catalytic domain of a protein, for
example the receptor. and it has the kinase activity. It is responsible for phosphorylating
tyrosine residues.
What is SH2 domain characterized by? - CORRECT ANSWER- Binds peptides with consensus
(positional information on C-terminal side of the phosphorylated tyrosine).
Very specific.
Mediates protein-protein interactions in cellular signalling cascades. Very common in proteins
outside the src family.
What do SH2 and SH3 domains have as a common funciton? - CORRECT ANSWER- They
mediate protein-protein interactions in cellular signalling cascades.
Very common in proteins outside the src family.
What is SH3 domain characterized by? - CORRECT ANSWER- Interacts with proline-rich peptide
targets (minimal consensus). Mediate protien-protein interatctions in the cellular signalling
cascade. Very common in proteins outside the src family.
What are PTB domains? - CORRECT ANSWER- (Phosphotyrosine binding domain)
CORRECT ANSWERS 2025-2026 || 100% GUARANTEED
PASS <BRAND NEW VERSION>
What is the reciprocal of RTK? - CORRECT ANSWER- Receptor Tyrosine Phosphatases. They
take the phosphate off the tyrosine residues to inactivate signalling cascades.
Ex. Transforming GF Beta superfamily of receptors, cell type dependent.
What is the major mechanism for receptor signal transduction? - CORRECT ANSWER- Tyrosine
kinase phosphorylation
RTK vs. Serine/Threonine Phosphorylation ? - CORRECT ANSWER- Tyrosine phosphorylation is
rare (1%) relative to serine/threonine residue phosphorylation. Tyrosine phosphorylation is the
major mechanism of receptor signal transduction.
What is the net effect of activated TKs? - CORRECT ANSWER- Tyrosine phosphorylation on
target proteins.
What do TK pathways mediate? - CORRECT ANSWER- Cell growth (growth factors),
differentiation, host defense, metabolic regulation, cell survival pathways (survival factors).
What are amplifiers of the TK pathways? - CORRECT ANSWER- PI3-K -> PIP3
PLC -> DAG and InsP3&Ca2+
,What are the 5 well-known enzyme-linked cell surface receptors? - CORRECT ANSWER- 1.
Receptor Guanylyl Cyclase: produces cGMP
2. RTK: phosphorylate tyrosine residues leading to association of signalling molecules and
cascade
3. TK Associated Receptors: associate with proteins having TK activity
4. Receptor Tyrosine Phosphates: Removes phosphate on tyrosine residues
5. Receptor Serine/Threonine Kinases: phosphorylate specific Serine/Threonine residues on IC
signalling molecules
How are RTK and TK Associated Receptors different? - CORRECT ANSWER- RTK phosphorylate
tyrosine while associated receptors bind/find proteins with TK activity to initiate the cascade of
signalling.
What are RTK mediated actions in the cell? - CORRECT ANSWER- regulation of cell
proliferation, differentiation, and cell motility, promotion of cell survival and modulation of
cellular metabolism.
TKs exist in either the cytosol or as transmembrane receptors, what are the differences in the
two types? - CORRECT ANSWER- Cytosol receptors have an src N-terminal region. Cytosol has
no membrane spanning domain.
TM receptor has a single membrane spanning hydrophobic TM domain. Ex) Epidermal GF RTK.
What is src? - CORRECT ANSWER- Src is a non-receptor TK, so it does not span a membrane. It
is a tyrosine kinase. And although it is cytoplasmic TK it can still bind to activated RTKs.
What is contact inhibition confluency? - CORRECT ANSWER- Stops Src domains signalling and
therefore cells stop dividing.
, If there is an issue then cancer can result and mutation causes an inhibition of the stop signal so
the cells keep growing and dividing.
What are SH domains? - CORRECT ANSWER- Src homology domains. Src and other proteins
that have src-homology domains can bing to activated RTKs.
What are the different SH domains in proteins? - CORRECT ANSWER- There are SH1, SH2 and
SH3 domains.
What isSH1 domain characterized by? - CORRECT ANSWER- Catalytic domain of a protein, for
example the receptor. and it has the kinase activity. It is responsible for phosphorylating
tyrosine residues.
What is SH2 domain characterized by? - CORRECT ANSWER- Binds peptides with consensus
(positional information on C-terminal side of the phosphorylated tyrosine).
Very specific.
Mediates protein-protein interactions in cellular signalling cascades. Very common in proteins
outside the src family.
What do SH2 and SH3 domains have as a common funciton? - CORRECT ANSWER- They
mediate protein-protein interactions in cellular signalling cascades.
Very common in proteins outside the src family.
What is SH3 domain characterized by? - CORRECT ANSWER- Interacts with proline-rich peptide
targets (minimal consensus). Mediate protien-protein interatctions in the cellular signalling
cascade. Very common in proteins outside the src family.
What are PTB domains? - CORRECT ANSWER- (Phosphotyrosine binding domain)
