LECTURE 10 - CELL ADHESION

simply define cell adhesion

the ability of cells to bind to other cells or the ECM via specialised adhesion molecules on the cell surface

what are the 2 major cell adhesion categories

cell cell adhesion

cell ECM adhesion

describe the 2 types of cell cell adhesion

stable; long lasting

transient; momentary

what is cell cell adhesion the result of

multiple binding events between different adhesion molecules and their ligands

why is cell cell adhesion important in terms of redundancy

the system will still be able to function because more than 1 cell has the ability to do the job, as cells are connected

what does expression of adhesion molecules depend on

1. cell differentiation

2. cell activation

3. cytokines

4. cross talk from other adhesion molecules

what protein complexes form when adhesion molecules bind to ligand receptors

adhesion molecules

signalling molecules

cytoskeletal components

what are the 4 main adhesion molecule families

cadherins

integrins

immunoglobulin superfamily members

selectins

what does IgSF stand for

immunoglobulin super family

what type of adhesion are cadherins involved in

cell cell adhesion

which adhesion molecules depend on calcium ions

cadherins

integrins

selectins

what does it mean for cadherins to bind homophilically

bind to the same cadherin type on an adjacent cell

what are the 3 classical cadherins

E-cadherin

N-cadherin

P-cadherin

where are E-cadherins found

epithelial cells

where are N-cadherins found

neurons and muscle

where are P-cadherins found

placenta and epithelium

what is the role of catenins

to link cadherins to the actin cytoskeleton of the cell

explain the structure of catenin cadherin linking

the cytoplasmic cadherin tail connects to the beta-catenin

the beta-catenin is joined to the alpha catenin

the alpha catenin binds to the actin cytoskeleton

what do all cadherin family members have

copies of the extracellular domain repeat

what part of cadherin members varies

the intracellular domain

describe the cadherin zipper

when molecules on opposing cells interlock like a zipper due to N-regions linking at cell cell junctions

where are desmosomes found

in most mature epithelia

what is the function of desmosomes

to rivet all the cells together

what kind of cell adhesion are integrins involved in

both cell cell and cell ECM adhesion

describe the structure of integrins

heterodimer; made of alpha and beta subunits which are non covalently bound

which integrin subunit contributes to ligand binding

both the alpha and the beta subunit, meaning both must be present for binding to occur

what divalent cations other than calcium do integrins rely on

magnesium and manganese