Question

Binding of a signal to the receptor tyrosine kinase DIRECTLY, initially causes:

Answer 1

Answer - The receptor tyrosine kinases are the largest class of membrane receptors involved in various signalling pathways. The receptor has kinase activity means it has ability to phosphorylate its targets. Therefore, when a signal binds to the receptor tyrosine kinase (RTK) DIRECTLY, initially causes cross-linking means the RTKs in neighbor associate with each other results in crosslinked dimers. This cross-linking further activates their kinase activity where the tyrosine group of one RTK is phosphorylated by the other RTK and so on throgh cross-phosphorylation. At later stage or after cross-phosphorylation, it activates various signalling pathways as diverge intracellular proteins invoved in several signalling pathways, bind to cytoplasmic tails of the phosphorylated RTKs and activates the particular pathway.

The figure given below shows the cross-linking of the receptor tyrosine kinase after binding to the signal molecules -