Signal Transduction Pathway

Signal Transduction

The transmission of molecular signals from outside the cell into the cell via cell-surface receptors.

Receptors

Proteins found in the cytoplasm, nucleus, or cell membrane that bind to ligands and initiate signal transduction.

Ionotropic Receptors

Transmembrane ion channels that open in response to ligand binding.

Metabotropic Receptors

Use signal transduction mechanisms to activate a series of events using secondary messenger chemicals.

Enzyme-Linked Receptors

Receptors with intrinsic enzymatic activity or associated with intracellular enzymes.

GPCRs

Receptors coupled to G proteins that modulate the activity of ion channels and enzymes.

Ligand-Gated Receptors

Receptors that allow specific ions to flow freely in response to binding of a chemical messenger.

Intracellular Receptors

Receptors located within a cell that, when activated, result in gene transcription.

G Protein Pathway

Involves the activation of G proteins, which modulate the activity of adenyl cyclase and protein kinase A.

cAMP Dependent Pathway

Activation of adenyl cyclase leads to the production of cAMP, which activates protein kinase A.

IP3/DAG Pathway

Activation of phospholipase C leads to the production of IP3 and DAG, which regulate calcium release and protein kinase C activation.

Soluble Kinases

Signal transduction pathway mediated by cytokine signals, involving JAK-STAT proteins.

JAK-STAT Pathway

Activation of JAKs leads to phosphorylation of STAT proteins, which translocate to the nucleus and induce gene transcription.

Tyrosine Kinase Pathway

Signaling molecules bind to tyrosine kinase receptors, leading to enzymatic reactions that carry the signal to the nucleus.

Steroid Hormone Pathway

Steroid hormones bind to receptor proteins and affect transcription by binding to hormone response elements on DNA.

G Proteins

Bind to receptors and activate target enzymes, generating second messengers.

Kinases

Bind to receptors and activate associated JAKs, which generate secondary messengers.

Enzymatic Messengers

Bind to enzymatic receptors and activate them, resulting in the generation of secondary messengers.

First Messengers

Ligands that bind to cell surface receptors and activate intracellular membrane pathways.

Second Messengers

Non-protein intracellular signaling molecules generated as a result of activation by first messengers, bringing about intracellular responses.