This document summarizes different types of cell junctions, including their structure, location, functions, and major proteins. It discusses tight junctions (zonula occludens), which form a seal between cells and control molecule passage. Adherent junctions (zonula adherens) firmly anchor cells together. Desmosomes (macula adherens) provide strong intermediate filament coupling between cells. Gap junctions allow exchange of molecules between cells. Hemidesmosomes anchor the cell cytoskeleton to the basal lamina.

6. “Objectives
Different types of cell junctions
Functions of different types of
cell junctions

7. Connection between the neighboring cells
or
contact between cell and extracellular
matrix
Cell junction

11. Basal domain
Lateral domain
Apical domain

12. Zonula occludens/
Tight junction
Zonula adherens/
Adherent junction
Macula adherens/
Desmosome
Gap junction
Hemidesmosome

13. Zonula occludens
Zonula adherens
Macula adherens
Gap junction

14. Belt
Something that occludes
Something that adheres
Spot
Desmos- bond
Soma- body
Zonula occludens
(tight junction)
Zonula adherens
Macula adherens
(desmosome)

15. Zonula occludens

16. Also called tight junction
Most apical of the junctions
A continuous ribbon-like structure
Forms a seal between adjacent cells
Zonula occludens (contd.)

17. Zonula occludens (contd.)

18. Zonula occludens (contd.)

19. Zonula occludens (contd.)

20. Seals adjacent cells to one another
Controls passage of molecules between cells
Separate apical and basolateral membrane domain
Forms different blood barrier
Zonula occludens (contd.)

21. Zonula occludens (contd.)
Blood-brain barrier

22. Zonula occludens (contd.)
Blood-thymic barrier
Tight junction
Reticulo-epithelial cell
Enothelial cell

23. Zonula occludens (contd.)
Blood-testis barrier

24. Zonula occludens (contd.)
Blood-CSF barrier

25. Zonula adherens

26. Also called adherent junction
Immediately below zonula occludens
Also encircles epithelial cells
Firmly anchor a cell to its neighbor cells
Zonula adherens (contd.)

27. Zonula adherens (contd.)

28. Zonula adherens (contd.)

29. Provide point linking to the cytoskeleton of
adjacent cells
Strengthen and stabilizes nearby tight junction
Zonula adherens (contd.)

30. Macula adherens

31. Also called desmosome
In lateral domain of cell membrane
Does encircles epithelial cells
Macula adherens (contd.)

32. Macula adherens (contd.)

33. Macula adherens (contd.)

34. Provide point of strong intermediate filament
coupling between adjacent cells
Strengthen the tissue
Macula adherens (contd.)

35. Macula adherens (contd.)
Macula adherens in skin

36. Gap junction

37. A communicating junction
In lateral domain of cell membrane
Permit exchange of molecules and ions
Gap junction (contd.)

38. Gap junction (contd.)

39. Gap junction (contd.)

40. Allows direct transport of small molecules and
ions from one cell to another
Gap junction (contd.)

41. Hemidesmosome

42. Anchoring junction
In basal domain of cell membrane
Resembles half desmosome
Hemidesmosome (contd.)

43. Hemidesmosome (contd.)

44. Hemidesmosome (contd.)

45. Anchor cytoskeleton of cell to the basal lamina
Hemidesmosome (contd.)

46. Points Zonula
occludens
Zonula
adherens
Macula
adherens
Hemidesmosome Gap junction
Major
transmembr-ane
protein
Occludin,
claudin
and
junctional
adhesion
molecules
E-cadherin,
catenin
complexes
Desmoglein
and
desmocollin
Integrins Connexin
Cytoskeletal
components
Actin
filaments
Actin filaments Intermediat
e
filaments
Intermediate
filaments
None
Channel protein Absent Absent Absent Absent Present
Communication Not
possible
Not possible Not possible Not possible Possible
Function Acts as a
barrier
Adheres the
adjacent
cells
Provides
strong
attachments
between
two cells
Adheres the cell
to the basal
lamina
Allows direct
transmission
of small
molecules
Summary

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