Cell and Molecular Biology: Signal Transduction

Which of the following plasma membrane receptors activate signaling pathways usually by forming molecular dimers that result in protein phosphorylation reactions upon binding of their specific ligand?

• G protein-coupled receptors

• Receptor tyrosine kinases

• Ligand receptors

When a __________ reaches its __________ , there is a specific means of receiving it and acting on the message. This task is the responsibility of specialized proteins called __________ .

• signaling molecule; receptor; G proteins

• signaling molecule; target cell; G proteins

• signaling molecule; target cell; receptors

G-proteins are classified as ________________,

• heterotrimeric

• tetrameric

• trimeric

. In GPCR signaling, the G protein Inactive alpha subunit gives up associated cAMP and takes up GDP, conformation changes again, released from beta/gamma subunits and interacts with target proteins.

• True

• False

G proteins are inactivated by ________ activity of alpha subunit.

• GTPase

• Receptor Tyrosine Kinases

______________cell-surface receptors with intracellular domains that have intrinsic enzymatic activity.

• Receptor Tyrosine Kinases (RTKs)

• Cell surface receptors

• Intracellular receptors

• G-coupled proteins receptors

Growth factors or mitogens stimulate RTKs to promote cell division and it is facilitated by the _________________.

• mitogen activating protein (MAP) kinase signaling cascade

• phospholipase C (PLC)/calcium pathway

The MAP Kinase signaling cascade begins the ___________.

• Ras GTPase

• RTK Activation

G-protein coupled receptors (GPCRs) have _______ transmembrane domains and are associated with an intracellular G-protein

• five

• seven

• nine

The target enzyme for Gq proteins is ____________.

• PI3-kinase

• adenylyl cyclase

• phospholipase C-beta