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#signal transduction

53 public questions tagged with this topic.

Regeneration -ll

IP3 in fertilization is generated by:

Phosphoinositide signaling during egg activation begins with hydrolysis of phosphatidylinositol 4,5-bisphosphate PIP2 residing in inner leaflet of plasma membrane. Enzyme catalyzing cleavage is phospholipase C activated via sperm-derived PLCzeta or Src kinase-mediated phosphorylation of PLCgamma after gamete fusion. Cleavage yields membrane-retained diacylglycerol activating protein kinase C and soluble inositol trisphosphate IP3 diffusing to endoplasmic reticulum triggering calcium release. Protein kinase C is downstream target not producer of IP3, dynein ATPase powers axonemal motility, Na+/

Ref: NCBI Bookshelf, Cell Signaling, Chapter 9: Phospholipase C cleavage of PIP2 to generate IP3 and DAG.

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Drosophila -ll

Activation of Toll receptor results from binding of:

Activation of Toll depends on extracellular cleavage of Spatzle precursor in perivitelline space. Ventrally restricted Pipe sulfotransferase modifies vitelline membrane enabling protease cascade comprising Gastrulation defective, Snake, Easter that processes Spatzle into active fragment. Active Spatzle binds Toll leucine-rich repeats inducing dimerization and recruitment of MyD88, Tube, Pelle. Gurken acts earlier in follicle cells, Dorsal acts downstream transcriptionally, Pipe modifies eggshell indirectly. Spatzle represents only physiological ligand whose ventral processing converts eggshell

Ref: Nature, Spatzle cleavage by Easter protease as Toll ligand - ventral activation of Toll receptor in Drosophila.

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Drosophila -ll

In Drosophila, Gurken protein interacts specifically with:

Gurken protein is secreted EGF family ligand transported to perinuclear region, where extracellular domain binds Torpedo receptor, Drosophila EGFR homolog expressed on follicle cells. Torpedo activation triggers Ras-MAPK and Pointed cascade repressing Pipe dorsally. Pipe, Toll, and Easter function downstream in vitelline modification and proteolysis and do not interact directly with Gurken. Specificity of Gurken-Torpedo interaction ensures spatial restriction of dorsal follicle fate, establishing symmetry break by nuclear migration that positions Gurken signal, linking oocyte cytoskeleton pola

Ref: Alberts, Molecular Biology of the Cell, Chapter 22: Gurken binding Torpedo EGFR - oocyte nucleus migration and_PIPE repression.

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Dictyostelium

cAMP degradation mediated by:

Temporal shaping of extracellular cAMP waves depends on regulated degradation preventing uniform saturation. Secreted phosphodiesterase PdsA hydrolyzes cAMP to AMP in extracellular medium, creating troughs between pulses that allow receptor resensitization and directional sensing. PdsA is expressed during aggregation from cAMP-inducible promoter, membrane-associated, and inhibited by specific inhibitor PdiA. RegA degrades intracellular cAMP, ACA synthesizes cAMP, PiaA couples TOR complex 2 to ACA activation. Without PdsA, cAMP accumulates uniformly, abolishing gradient, cells fail to aggregate

Ref: Journal of Cell Biology, PdsA extracellular phosphodiesterase - cAMP wave shaping and aggregation chemotaxis.

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Dictyostelium

cAMP receptors classified as:

cAMP receptors cAR1 through cAR4 are classical seven-transmembrane heterotrimeric G protein-coupled receptors with high homology to mammalian chemoattractant receptors. They couple to G alpha 2 and G beta-gamma complexes activating multiple effectors including adenylyl cyclase, phospholipase C, PI3K, and MAPK, coordinating chemotaxis and gene expression. They are not ligand-gated ion channels, receptor tyrosine kinases that autophosphorylate, or nuclear hormone receptors residing intracellularly. cAR1 possesses highest affinity, rapidly desensitizes, and establishes oscillatory dynamics essent

Ref: NCBI Gene, Dictyostelium cAR1 as GPCR - seven transmembrane and heterotrimeric G protein chemotaxis signaling.

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Glycolipid and Phospholipid

Which feature allows lipid rafts to regulate signal transduction?

Signal compartmentalization arises because cholesterol sphingolipid rich liquid ordered platforms concentrate specific proteins while excluding others lowering activation threshold facilitating downstream signaling. Cholesterol fills interstitial gaps between sphingomyelin saturated chains raising order parameter decreasing fluidity variance thickening bilayer promoting sequestration GPI anchored proteins dual acylated Src family kinases Fyn Lyn palmitoylated LAT adaptor PAG and flotillins. Extracellular ganglioside glycans form lattice galectins stabilizing clusters via multivalent interactio

Ref: Simons & Toomre, Nature Rev Mol Cell Biol 2000, Raft signaling dependence cholesterol sphingolipids and kinases.

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Plasma Membrane Proteins

Which transmembrane protein is a seven-pass receptor involved in signal transduction?

Seven-transmembrane receptor family also termed heptahelical receptors or G protein-coupled receptors comprises largest receptor superfamily in human genome over eight hundred members including rhodopsin-like class A, secretin class B and glutamate class C. Architecture consists of extracellular N-terminal domain ligand binding, seven hydrophobic alpha-helices TM1 through TM7 each nineteen to twenty seven residues traversing membrane with three extracellular loops ECL1-3 and three intracellular loops ICL1-3 and intracellular helix eight parallel to membrane interacting with heterotrimeric G pr

Ref: Rosenbaum et al., The Structure and Function of GPCRs, Nature 2009.

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Lipid Link Protein

Which lipid anchor type is involved in signal transduction and is found in Ras protein?

Ras small GTPases H-Ras, N-Ras, K-Ras are central hubs in growth factor signaling linking receptor tyrosine kinases to Raf-MEK-ERK MAPK cascade regulating proliferation, differentiation, survival and cytoskeletal remodeling. For signaling competence Ras must associate with inner leaflet of plasma membrane where it interacts with effectors. This localization depends on C-terminal CAAX prenylation. H-Ras, N-Ras, K-Ras4A undergo farnesylation of CAAX cysteine by farnesyltransferase forming thioether linked 15-carbon anchor, followed by RCE1 cleavage and ICMT methylation. Additional second signal

Ref: Hancock, Nat Rev Mol Cell Biol 2003, Ras membrane targeting; Prior et al., Cancer Res 2012.

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A Cell Signaling

ERK5 full activation requires

MEKK2 and MEK5, is consistent with established principles of cell signaling, receptor pharmacology and cellular regulation. Experimental measurements of binding parameters, genetic loss-of-function studies and pharmacological interventions all converge on the same interpretation. Related options address neighboring concepts but do not satisfy the precise criterion stated in the question.

Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)

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A Cell Signaling

Which conditions cause constitutive Ras signaling?

A and D, is consistent with established principles of cell signaling, receptor pharmacology and cellular regulation. Experimental measurements of binding parameters, genetic loss-of-function studies and pharmacological interventions all converge on the same interpretation. Related options address neighboring concepts but do not satisfy the precise criterion stated in the question.

Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)

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A Cell Signaling

Correct identification of Ras-MAPK components is

Grb2–SOS–Ras-GTP–ERK, is consistent with established principles of cell signaling, receptor pharmacology and cellular regulation. Experimental measurements of binding parameters, genetic loss-of-function studies and pharmacological interventions all converge on the same interpretation. Related options address neighboring concepts but do not satisfy the precise criterion stated in the question.

Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)

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A Cell Signaling

Receptor lacking intrinsic kinase activity is for

Growth hormone, is consistent with established principles of cell signaling, receptor pharmacology and cellular regulation. Experimental measurements of binding parameters, genetic loss-of-function studies and pharmacological interventions all converge on the same interpretation. Related options address neighboring concepts but do not satisfy the precise criterion stated in the question.

Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)

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