Enzyme-linked cell surface receptors

Enzyme-linked cell surface receptors

1. Definition

   • Transmembrane proteins
   • Extracellular ligand binding domain
   • Cytosolic domain has intrinsic enzymatic activity or associates with an enzyme
   • Each subunit has 1 TM domain
   • Often activates same signalling pathways as GPCR

2. At least 5 classes

   • Receptor tyrosine kinases
   • Tyrosine-kinase associated receptors
   • Receptor-like tyrosine phosphatases
   • Receptor serine/threonine kinases
   • Receptor guanylyl cyclases

3. Receptor tyrosine kinases

   • What domains bind phosphorylated tyrosine residues?
     • SH2 domains
     • Modular binding domains
   • Activate Ras-mediated protein kinase signalling

4. Tyrosine-kinase associated receptors

5. Receptor-like tyrosine phosphatases

6. Receptor serine/threonine kinases

7. Receptor guanylyl cyclases

   • Single pass transmembrane protein with extracellular ligand binding site
   • Intracellular guanylyl cyclase domain catalyses cyclic GMP formation
     • cGMP binds and activates cyclic GMP-dependent protein kinase (PKG) or ion channels
   • Signal molecules
     • Natriuretic peptides (NP's)
       • Regulate salt and water balance and dilate blood vessels
       • E.g.
         • Atrial natriuretic peptide (ANP)
         • Brain natriuretic peptide (BNP)
       • Involved in diseases such as hypertension

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