The C5b component is extremely labile, is not covalently bound to the membrane like C3b and C4b, and is rapidly inactivated unless it is stabilized by the binding of C6.

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

Two type of Cadherins:

1. Classical cadherin proteins

2. Nonclassical cadherin proteins

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

Extracellular region of a classical cadherin contains five copies of the cadherin domain separated by flexible hinge regions

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

Ca2+ ions bind to sites near each hinge and prevent it

from flexing, so that the whole string of cadherin domains behaves as a rigid and slightly curved rod to generate cell–cell adhesion

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

In absence of Ca2+, 

the hinges can flex, the structure becomes floppy & adhesion fails

TLS Online TPP Program

#Id: 10069

#Unit 4. Cell Communication and Cell Signaling

Each classical cadherin molecule contains: 

A single TM domain

A short C-terminal cytosolic domain

Five extracellular “cadherin” domains (EC1–EC5)

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

Three classes of classical cadherins: 

E-cadherin -present on epithelial cells

N-cadherin - present on nerve, muscle and lens cells

P-cadherin - present on cells in the placenta & epidermis