recognition response Flashcards
what regulates recognition and response
Recognition & response are regulated by
surface receptors and intracellular proteins
what do surface receptors on immune cells recognize
Surface receptors on immune cells recognize antigens (B & T cells) or
patterns (innate cells)
activation of the receptor induces a response in the cell (signal transduction)
how do receptors interact with ligands
through non covalent interactions
h bond
VDW hydrophobic interactions
ionic bond
how is the strength of an interaction quantified between a receptor and a ligand
the dissocaition constant kd
what does a high and low kd value mean
the lower the kd, the higher the affinity of interaction
Most enzyme ligand interactions: Kd range 10 -3 to 10 -5 M
Ab – Ag interactions: Kd as low as 10 -12 M
what is equilibrium analysis used for
to determine antibody affinity
affinity
interaction between one ligand and receptor
avidity
overall strength of all interactions during multivalent binding
what regulates key steps in receptors binding to antigens
Key steps are regulated by
phosphorylation of proteins to form
docking sites, activate enzymes, or
promote degradation/stabilization of
proteins
what does receptor clusering by multivalent Ags do
activates signal transduction
a) individual receptors bind a multivalent ligand and nycleate receptor cluster formation
b) multivalent ligand mediates cluster formation
what do membrane microdomains do
Membrane microdomains increase organization and efficiency of receptor activation/clustering
what is an example of a membrane mircodomain
lipid raft
what are to ways of changing the affinity of receptors for thier ligands
Combining different receptor sub-units can change the affinity of receptors for their ligand
Changing the level of
receptor on the cell
surface can also vary
the response of the
cell
what is a protein domain commonly shared by many receptors
Many receptors share a
common protein domain-
Immunoglobulin (Ig)
domain
what is the immunoglobulin domain and what is its structure
The Ig domain was first described in Antibodies, which is why it
was named “immunoglobulin domain”
The Ig domain is sandwich of 2 b sheets with loops connecting the anti-parallel b strands
how do B lymphocytes interact with antigens
via the B cell receptor
this consists of an Ab that recognizes the antigen and molecules inserted into the membrane that communicates with the inside of the cell (signal)
BCR and co-receptors
Co-receptors can accelerate or change the
signal sent through the BCR
how do T cells recognize antigens
The T cell receptor and co-receptors allow interaction of T cells with peptide Ag;
when the Ag is presented by APC
Molecules that communicate with
the inside of the cell (signal)
what do innate immune cells recognize
Innate immune cells recognize pathogen associated molecular patterns (PAMPs) via pattern recognition
receptors (PRR)
what are cytokines
Group of low-molecular weight regulatory proteins that function as the ʻmessengers of the immune systemʼ
what cells are cytokines
Includes:
* Interleukins (secreted by leukocytes & act on
other leukocytes)
* Monokines (secreted by monocytes &
macrophages)
* Lymphokines (secreted by lymphocytes)
* Chemokines: related but regulate cell migration
how do cytokines act
Cytokines act in autocrine, paracrine, or endocrine fashion
how much. cytokines is required to have an effect
Cytokine RECEPTORS have
very high affinity for the
cytokine, SO cytokines can
have biological effects at
picomolar amounts
pleiotropy
same cytokine acts on different cels to have different effects
