Figure 6.14. The widely used RTK signal transduction pathway.

Figure 6.14

The widely used RTK signal transduction pathway. The receptor tyrosine kinase is dimerized by the ligand, which causes the autophosphorylation of the receptor. The adaptor protein recognizes the phosphorylated tyrosines on the RTK and activates an intermediate protein, GNRP, which activates the Ras G protein by allowing the phosphorylation of the GDP-bound Ras. At the same time, the GAP protein stimulates the hydrolysis of this phosphate bond, returning Ras to its inactive state. The active Ras activates protein kinase C (PKC), which in turn phosphorylates a series of kinases. Eventually, the activated ERK kinase alters gene expression in the responding cell by phosphorylating certain transcription factors (which can then enter the nucleus to change the types of genes transcribed) and certain translation factors (which alter the level of protein synthesis). In many cases, this pathway is reinforced by the release of calcium ions. A simplified version of the pathway is depicted on the left.

From: Cell Surface Receptors and Their Signal Transduction Pathways

Cover of Developmental Biology
Developmental Biology. 6th edition.
Gilbert SF.
Sunderland (MA): Sinauer Associates; 2000.
Copyright © 2000, Sinauer Associates.

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