Cell adhesion & ECM Flashcards
What are the 3 main classes of junctions?
Anchoring - adhesion of cell-cell or cell-extracellular membrane adhesion
Occluding - create impermeable or semipermeable barrier between adjacent epithelial cells
Communicating - channels that mediate electrical signaling
What are the 4 types of anchoring junctions?
Adherens Junction
Desmosome
Hemidesmosome
Focal Contact
Function and adhesion molecule of:
Adherens Junction
Cell-Cell adhesion
Cadherins
Associated with ACTIN
Stabilized by Desmosomes
Function and adhesion molecule of:
Desmosome
Cell-Cell adhesion Desmosomal Cadherins (desmoglein, desmocollin) Associated with intermediate filaments
Function and adhesion molecule of:
Hemidesmosome
Basal Surface of Cell-Underlying ECM
Integrins (which interact with laminin and collagen)
Associate with Intermediate filaments
Function and adhesion molecule of:
Focal Contacts
Found between cells basal surface and ECM
Adhesion of Cell-Substratum
Integrins
Associated with actin
Function and Transmembrane proteins of:
Occluding Junction / Tight Junctions
Forms a regulated seal between plasma membrane of adjacent cells. Luminal surface from intercellular space and basal surface
TM proteins = claudins and occludin
ZO proteins link TM proteins to ACTIN
Junctional Complex is composed of
Tight Junction
Adherens Junctions
Desmisomes
Function and adhesion molecule of:
Gap Junctions
Hydrophilic Channel (small only) Formed by 2 connexons (composed of connexin proteins) Function: intercellular communication
4 Major Families of Cellular Adhesion Molecules (CAMs)
Cadherin
Immunoglobulin
Integrin
Selectin
Characteristics of cadherins
Cell-Cell (homophilic)
Bind to catenins, which bind to actin (necessary for function)
Beta-catenin stabilizes and also plays a role in cell turnover
Calcium dependent
Characteristics of Immunoglobulin Super Family
Cell-Cell (homo-and hetero phillic)
Interacts with Self or integrins
Adhesion molecule: ICAM & VCAM
Bind to actin
Characteristics of Integrins
Cell-Cell, Cell-ECM
Associated with actin & intermediate filaments
Characteristics of Selectins
Cell-Cell in bloodstream (hetero)
Only bind to carbohydrates
Associated with ACTIN
Function of fibroblasts?
Secretion of ECM proteins
Components of ECM
Collagen Basement Membrane Laminin Glycosaminoglycans Proteoglycans Elastic Fibres Fibronectin Fibrinogen
Function of Collagen
Strength and stability of connective tissue
Basement membrane function
Anchors epithelial cells to connective tissue
Connected to cells through integrins
Laminin Function
Major component of basement membrane
Mediates hemidesmosomal attachments
Glycosaminoglycans Function
Long Carb. Chain (polysacch) Anionic groups (strong negative charge) Hyaluronic Acid = non-sulphated GAG (helps cartilage resist compression)
Elastic Fibres function
Allow recoil of stretched tissue
Elastin and fibrillin = major protein components
Fibronectin function
Attaches cells to ECM components via integrins
Fibrinogen function
protein component of blood clots
binds cells to other ecm components
Cleavage by thrombin
