notes

1. TRANSMEMBRANE
ENZYME LINKED
RECEPTORS
Akash kumar
Roll no.- 18
MBBS BATCH 2023

2. OBJECTIVE
 Introduction
 Structure of receptor
 Transmembrane enzyme linked receptor
 Mechanism of Action

3. INTRODUCTION
 Transmembrane enzyme-linked receptors have enzymatic
activity in their intracellular portion
 The enzyme is mainly tyrosine kinase, e.g. receptor tyrosine
kinases for insulin, epidermal growth factor, etc.).

4. STRUCTURE OF RECEPTOR
 This class of receptors are utilized primarily by peptide hormones.
 These receptor are made up of a large exatracellular ligand
binding domain connected through a sing le transmembrane
helical peptide chain lo an intracellular sub-unit having enzymatic
property.
 Transforming growth factor (TGF) receptor
 And few others are serine/threonine which phosphorylate
serine/threonine residues of the target proteins.

5. TRANSMEMBRANE ENZYME
LINKED RECEPTORS
 The enzyme at the cytosol ic side is generally a protein
kinase, but can a lso be guanylyl cyclase in few cases.
 The commonest protei n kinases arc the ones which
phosphorylate tyrosine residues on the substrate proteins and
are called ·receptor tyrosine kinases' (RTKs)
 Inhibitors of specific RTKs involved in growth factor signaling
are a new class or targeted anticancer drugs.

6. MECHANISM OF ACTION

7. FUNCTION
 A large number of intracellular signaling proteins have SH2
domains.
 By controlling phosphorylation of key enzymes, ion channels,
transporters, etc. the RTK are able to regulate diverse cell ular
functions including metabolic reactions, cell growth and
differentiation.
 One of the SH2 domain enzymes is phospholipase cy (PLcy) which
is activated by certain RTKs, and which, like PLcp, generates f P,
and DAG as second messengers for response effectuation.

8. ANOTHER FEATURES
 Their dimerization also promote receptor internalization
degradation in lysosomes and down regulation if activation is
fast enough.
 Mutations interfering with such down-regulation contribute
co development of certain malignancies.
 In place of protein kinase the enzyme can also be guanyly l
cyclase (GC), as in the case of atrial natriuretic peptide (A P).
 Agonist activation of the receptor generates cGMP in the
cytosol as a second messenger, which in turn activates cGM P-
dependent protein kinase (PKc) and modulates cellular
activity.

9. SUMMARY