cellular polarity

Question 1

what is cellular polarity?

Answer 1

the asymmetric arrangement of cellular components which defines cellular shape and function

Question 2

how is cell polarity generated?

Answer 2

E-cadherin recruited by nectin based cell-cell adhesions forming adherens junctions
adherens junction recruits JAM’s to the apical side
PAR3 polarity complex binds to JAM and recruits TJ proteins to apical domain
TJ formed resulting in cell-cell adhesions and a pinch point between the apical and basolateral domains
crumbs complex (CRB3) localises to apical domain above the TJ

Question 3

what is PATJ?

Answer 3

a protein in the CRB3 complex which recruits the TJ scaffold proteins zona occludens.

Question 4

how does mutual exclusion of complexes maintain polarity?

Answer 4

CRB3 and PAR3 remain apical
scrib remains basal
due to mutual exclusion from the opposing domain
maintains cell asymmetry and polarity

Question 5

what regulates scrib and CRB3 function?

Answer 5

phosphorylation by aPKC