Signal transduction

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Lipid signaling:

Ceramide

  • Sphingomyelinase (SMase) or sphingomyelin phosphodiesterase is a hydrolase involved in sphingolipid metabolism. It catalyzes the breakdown of sphingomyelin (SM) to phosphocholine and ceramide[1].
  • Acid-beta-glucosidase or glucosylceramidase is a lysozomal enzyme (EC number 3.2.1.45), which cleaves glucosylceramide to glucose and ceramide. It catalyzes hydrolysis of the sphingolipid, , to at the acidic pH prevailing within the lysosome. .
  • The molecular function of galactosylceramidase is hydrolysis of a O-glycosyl bond to remove galactose from ceramide and other sphingolipids.

Sphingosine-1-Phosphate

Glucosylceramide

Phosphatidylinositol bisphosphate (PIP2)

Phosphatidylinositol 4,5-bisphosphate (PIP2) binds to and directly activates inwardly rectifying potassium channels. Inward rectifier KCh.

Signaling Pathways:

ABA Signaling Pathway

Protein Kinases:

Tyrosine kinase

  • Receptor tyrosine kinases
  • Tyrosine kinase
  • Janus kinase or tyrosine-protein kinase JAK (JAK) are nonreceptor tyrosine kinases which transduces cytokine-mediated signals via the JAK-STAT pathway. The JAK-STAT pathway transmits signals through the cell membrane to DNA promoters thus causing transcription.

Protein kinase C

MAPK

CAMP-dependent protein kinase

Chemotaxis:

Mechanotransduction:

Thermoception

Transient receptor potential channels

Voltage-gated channels

Visual phototransduction

Light is detected by rhodopsin in rod and cone cells.

Photoreceptor pigments

Circadian clock

Protein phosphatases:

Second messengers

cAMP is second messenger

CAMP-dependent protein kinase

IP3 is second messenger

Receptors that activate this pathway (Phospholipase C) are mainly G protein-coupled receptors coupled to the Gαq subunit, including:

  • 5-HT2 serotonergic receptors (5-hydroxytryptamine receptor#Structural highlights/Specific Function of 5-HT2B).
  • α1 adrenergic receptors
  • Calcitonin receptors
  • Histamine H1 receptor. The H1 receptor is a histamine receptor belonging to the family of rhodopsin-like G-protein-coupled receptors. The H1 receptor is linked to an intracellular G-protein (Gq) that activates phospholipase C and the inositol triphosphate signaling pathway. When a ligand binds to a G protein-coupled receptor that is coupled to a Gq heterotrimeric G protein, the α-subunit of Gq can bind to and induce activity in the PLC isozyme PLC-β, which results in the cleavage of PIP2 into IP3 and DAG.
  • Metabotropic glutamate receptor 1 and metabotropic glutamate receptor 5 belong to group I and activate phospholipase C. For details see Metabotropic glutamate receptor 5.
  • M1, M3, and M5 muscarinic receptors. Muscarinic acetylcholine receptors (mAChR) contain 5 subtypes M1-M5. Subtypes M1, M3, M5 activate phospholipase C which leads to activation of protein kinase C.
  • Inositol 1,4,5-Trisphosphate Receptor

Paracrine signaling: fibroblast growth factor (FGF) family, Hedgehog family, Wnt family, and TGF-β superfamily

Fibroblast growth factor and Fibroblast growth factor receptor (FGFR). FGFR belongs to Receptor tyrosine kinases, class V.

Sonic Hedgehog


Ca2+ signalling processes

H+/K+-ATPase signal pathway (acetylcholine, histamine, and gastrin) activates the pump in order to move the vesicles toward the lumen.

Proton pump

Signal transducing adaptor proteins (STAPs)

GTPase

The Mitogen-activated protein kinase cascade

MAPKs are involved in directing cellular responses to a diverse array of stimuli, such as mitogens, osmotic stress, heat shock and proinflammatory cytokines. They regulate cell functions including proliferation, gene expression, differentiation, mitosis, cell survival, and apoptosis.

Inflammatory response

Allostery

ATPase


Nicotinic Acetylcholine Receptor, PDB code 2bg9

Drag the structure with the mouse to rotate

ReferencesReferences

  1. Chatterjee S. Neutral sphingomyelinase: past, present and future. Chem Phys Lipids. 1999 Nov;102(1-2):79-96. PMID:11001563

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Alexander Berchansky