Cell Signaling

Which form of intercellular signaling involves a signaling cell secreting local mediators that act only on cells in the immediate environment?

What concentration of signal molecules is typically required for them to act, and what corresponding affinity do their receptors usually have for them?

The largest class of molecular switches in intracellular signaling consists of proteins that are activated or inactivated by what process?

What is the function of a GTPase-activating protein (GAP)?

Approximately how many G-protein-coupled receptors (GPCRs) are there in humans?

How does cholera toxin cause the severe diarrhea that characterizes cholera?

How does an increase in cytosolic Ca2+ concentration lead to the activation of protein kinase C (PKC)?

Which property of CaM-kinase II allows it to function as a molecular memory device, remaining active even after the initial Ca2+ signal has decayed?

GPCR desensitization, where a target cell's response diminishes over time despite a prolonged signal, depends on the phosphorylation of the GPCR by which class of kinases?

What is the primary role of the protein Grb2 in the RTK-Ras signaling pathway?

In the mammalian Ras–MAP kinase signaling pathway, what are the common names for the three kinases that form the module, in order from upstream (activated by Ras) to downstream?

How does the PI 3-kinase–Akt signaling pathway promote cell survival?

Which class of receptors acts through cytoplasmic tyrosine kinases, such as JAKs, because they themselves lack an intrinsic kinase domain?

What is the direct consequence of a TGF-beta dimer binding to its receptor complex?

In the Notch signaling pathway, what is the role of the protease complex gamma-secretase?

What is the primary function of the degradation complex containing APC, axin, GSK3, and CK1 in the Wnt/beta-catenin pathway?

In the Hedgehog signaling pathway, where are most of the early signaling components, such as Patched and Smoothened, concentrated?

How do pro-inflammatory signals like TNF-alpha lead to the activation of the latent transcription regulator NF-kappa-B?

How do small hydrophobic signal molecules like steroid hormones differ from most other extracellular signals in their mechanism of action?

In the cyanobacterium Synechococcus elongatus, the core circadian oscillator is composed of which three proteins?

In plant signaling, what is the largest family of cell-surface receptors?

What is the mechanism by which the gaseous plant hormone ethylene influences gene expression?

What is the key feature of a positive feedback loop in a signaling pathway when the feedback is strong?

How does an activated GPCR act as a guanine nucleotide exchange factor (GEF) for its associated G protein?

What is the typical structure of a G-protein-coupled receptor (GPCR)?

In the IP3 signaling pathway, what is the direct role of inositol 1,4,5-trisphosphate (IP3)?

Approximately what percentage of human proteins contain covalently attached phosphate?

What type of interaction domain allows signaling proteins to bind to the charged head groups of specific phosphoinositides produced in the plasma membrane?

In vertebrate vision, what is the immediate effect of light-induced activation of rhodopsin in the disc membrane of a rod cell?

What percentage of human tumors express hyperactive mutant forms of Ras proteins?

In the activation of Ras by a Receptor Tyrosine Kinase (RTK), what is the function of the protein Sos?

What is the role of the PTEN phosphatase in the PI 3-kinase signaling pathway?

Mutations in the Apc gene, which are found in 80 percent of human colon cancers, lead to the accumulation of which signaling protein?

The activation of a transcription regulator CREB by PKA is a key step in transforming a short cAMP signal into a long-term cellular change. What does CREB stand for?

In the JAK-STAT pathway, what is the dual role of the SH2 domain on a STAT protein?

How is the speed of a cellular response to the removal of a signal related to the turnover rate of the intracellular molecules the signal affects?

In the Hedgehog pathway, what is the proposed mechanism by which the Patched receptor inhibits the Smoothened protein?

Signaling systems can convert a gradual increase in an extracellular signal into an abrupt, all-or-none response. This sharpening of the response becomes more pronounced as what condition is met?

What is the primary mechanism of action for the plant hormone auxin?

What are the two major types of protein kinases in eukaryotic cells, categorized by the amino acids they phosphorylate?

What is the function of the protein calmodulin?

How many human RTKs have been identified, and into how many structural subfamilies are they classified?

In the context of intracellular signaling, what is a 'second messenger'?

Which protein complex in the Wnt pathway is directly targeted by mutations in 80% of human colon cancers?

What is the function of scaffold proteins in signaling pathways?

In the activation of the EGF receptor, a type of RTK, how does the kinase domain of one receptor monomer activate the other in the dimer?

Which family of Ras superfamily monomeric GTPases is primarily responsible for regulating the actin and microtubule cytoskeletons?

What is the key protein kinase that integrates inputs from multiple sources like growth factors and nutrients to regulate cell growth, and is the target of the drug rapamycin?

What is the effect of a short delay versus a long delay in a negative feedback loop on a signaling response?

When a cell is deprived of the appropriate extracellular survival signals, what process does it typically undergo?