BIOC 212 Lecture Notes - Lecture 24: Talin Protein, Keratinocyte, Filamin
29 May 2018
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Cell Junctions & Cell Adhesion IV
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Desmosomes
• Dense plaque: plakoglobin & desmoplakin
o Made of adaptor proteins
o TM proteins interacting with each other, adaptor proteins and then
cytoskeletal elements
• Same principle, partly different molecules
• Transmembrane adhesion proteins: desmoglein & desmocollin (cadherin family)
• Antoantibodies against desmosomal cadherin proteins:
• Phemphigous vulgaris: autoimmune blistering that affects skin & mucous
membranes
o Antibodies against desmoglein (cadherin proteins)
• Antibodies circulate in body, bind strongly to cadherins and interfere with
cell-cell interaction
• Lots of antibodies bind and cause cells to detach
o Cells become separated from each other and epidermis becomes unglued
(acanthylosis)
Desmosomes Plaque
• Structural components of desmosome
o On cytoplasmic surface of each interacting PM, have dense plaque
composed of mixture of intracellular anchor proteins
o Bundle of keratin intermediate filaments attached to surface of each plaque
• TM adhesion proteins from cadherin family bind to the plaques
o Interact through the extracellular domains to hold adjacent membranes
together by Ca2+-dependent mechanism
• Importance of anchoring proteins --affinities, mutations
• Desmoglein & desmocollin are members of cadherin family of adhesion proteins
o Their cytoplasmic tails bind plakoglobin (g-catenin), which in turn binds
desmoplakin
• Provide anchor point for long extended desmoplakin dimers
• Tied by coiled-coiled region
• Creates a bridge to intermediate filaments
o Desmoplakin binds the sides of intermediate filaments; tying desmosomes to
these filaments
Anchoring Junctions --Focal Adhesions
• Mesenchymal cells (muscle, fibroblasts, etc.)
o Same principle but with variations adapted to need of cells
