Page 518 - First Aid for the USMLE Step 1 2020, Thirtieth edition [MedicalBooksVN.com]_Neat

474 section iii Musculoskeletal, skin, and connective tissue ` dERmatology Musculoskeletal, skin, and connective tissue ` dERmatology

Epithelial cell junctions
Tight junctions (zonula occludens) A –prevents
A Claudin/
occludin paracellular movement of solutes; composed of
claudins and occludins.
Apical Adherens junction (belt desmosome, zonula
Tight junction
adherens) B –forms “belt” connecting actin
B cytoskeletons of adjacent cells with CADherins
(Ca -dependent adhesion proteins). Loss of
2+
E-cadherin promotes metastasis.
Adherens junction Cadherins Desmosome (spot desmosome, macula adherens)
C C –structural support via intermediate filament

Intermediate interactions. Autoantibodies to desmoglein 1
filaments and/or 3 Ž pemphigus vulgaris.
Desmosome Gap junction D–channel proteins called
D connexons permit electrical and chemical
communication between cells.
Connexon Hemidesmosome E –connects keratin in basal
100 nm cells to underlying basement membrane.
Gap junction
Autoantibodies Ž bullous pemphigoid.
Basal E (Hemidesmosomes are down “bullow.”)
Integrin Integrins–membrane proteins that maintain
Fibronectin/ integrity of basolateral membrane by binding
laminin
Hemidesmosome ECM/collagen to collagen, laminin, and fibronectin in
basement membrane.

FAS1_2019_11-Musculo.indd 474 11/7/19 5:24 PM