MEDI7111 Lecture Notes - Lecture 6: Adenylyl Cyclase, Ion Channel, Human Chorionic Gonadotropin
Endocrine 6
Hormone Classification & Receptor Types
Classes Non-Steroid Hormones Steroid Hormones
Examples Amines
Catecholamines
Thyroxin
Serotonin
Polypeptides
TRH, ADH, GnRH, GH,
Insulin, Glucagon, PTH,
ACTH, Calcitonin, LH,
FSH, TSH, hCG
Aldosterone
Cortisol
Testosterone
Estrogen
Progesterone
Receptor
Location
Cell surface receptors Intracellular receptors
Receptor
Types
Ion channel linked receptors
Mainly used in neurological signalling
Hormone binds to receptor to cause a
conformational change in the shape of the
channel, allowing (select) ions to pass through
Receptors for steroid
hormones are mostly
found in the nucleus,
where once bound to their
hormone ligand, bind to
DNA to regulate
transcription.
They often involve dozens
of genes.
Enzymatic receptors
Used by insulin and growth factors
Ligand binding triggers dimerization,
synergistically phosphorylate the other
receptor leading to a signalling cascade,
results in nuclear activity
GPCRs
Used by hormones requiring slower response
times
The receptor is not an enzyme, when the
ligand binding site is occupied, the G protein
attached is activated (GDPGTP).
From here it has 2 options:
(1) It passes a phosphate group onto
adenylate cyclase to become cAMP, which
triggers a PKA phosphorylation cascade
(think cAMPPKA)
(2) It uses calmodulin to trigger the PKC
phosphorylation cascade
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