Types of Cellular Receptors Flashcards
List the Types of Cellular Receptors.
Gated Ion Channel Enzyme Linked Receptor G-Protein Linked Receptor Enzyme Associated Receptor Steroid/ Intracellular Receptor
ION CHANNEL-LINKED RECEPTORS (Ligand-gated channels) -
They allow the passage of ions across the cell membrane. They require a ligand to bind to the receptor to open them up and allow the ions to flow through.
List the Characteristics of Ion Channel Linked Receptors.
- Very rapid transport through a channel (~million ions/sec);
- High selectivity;
- Are not permanently open – opening regulated by “gates”, that transiently open in response to stimuli.
G PROTEIN-LINKED RECEPTORS -
Transmit signals via intermediary guanine nucleotide binding proteins (G proteins)
When a receptor binds to a signaling molecule, G protein binds to the receptor and changes conformation. That conformation change allows the G protein to bind/fit into a specific enzyme and activate that enzyme.
Second Messengers -
One or more small intracellular molecules that are activated by a chain of events caused by Most of the G protein-linked receptors
List the 2nd Messengers.
They are also known as “intracellular mediators”.
- cyclic AMP
- Ca2+
- cyclic GMP
- Diacyl Glycerol
- Phosphoinositol diphosphate
What are the most common Second Messengers?
cAMP and Ca2+
What does cAMP activate?
It activates Protein Kinase A (PKA)
Describe how Protein Kinase A (PKA) gets activated.
- 4 cAMP bind the 2 Regulatory subunits of PKA.
2. This causes the activation and release of the 2 Inactive Catalytic subunits.
Describe the structure of Protein Kinase A (PKA).
Inactive PKA is composed of 2 parts. A Regulatory Subunit (2) and Inactive Catalytic subunit (2).
What are 3 ways that Ca2+ can get into the cell?
- Na+ driven Ca2+ exchanger (an antiport)
- Ca2+ pump (in ER)
- Simport (H+/Ca2+ pump in mitochondrion)
What are the Ca2+ binding proteins?
Troponin C
Calmodulin
What are the Ca2+ sensors proteins?
S100B
GCAPs
Neurocalcin Delta
What is the EF hand?
It is a structural motif of Ca2+ binding proteins
Enzyme Linked Receptors -
They can become enzymes or associate w/ an enzyme.
The are receptors that are far from each other. But in the presence of a signal, they come together to form a receptor. This new receptor either has:
a) a catalytic domain or
b) activates a linked enzyme
