BIOC 212 Lecture Notes - Lecture 27: Dissociation Constant, Ethylenediaminetetraacetic Acid, Elastase
29 May 2018
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Cell Junctions & Cell Adhesion VII
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Some Members of Cadherin Superfamily
• Cadherins: Ca2+ mediated cell-cell adhesion in vertebrates & invertebrates
• Classical cadherins; at least 17 in Homo sapiens
o E-cadherin (epithelial cells)
o N-cadherin (nerve & muscle cells)
o P-cadherin (placenta, epidermis)
o Are found in other tissues as well --i.e. N-cadherin in fibroblasts & E-cadherin
in parts of brain
• Non-classical cadherins; large number
o More than 70 expressed in the brain (protocadherins)
o Desmosomal cadherins (previously discussed)
• All vertebrates seem to express 1+ cadherin
o Main adhesion protein holding cells together in embryonic development
o Adhesive + signaling functions (intracellular domain)
Cadherin Superfamily --Structural Variety
• Classical cadherins with extracellular, TM and intracellular domains
• Extracellular portion: contains multiple copes of green cadherin domain
o Related to immunoglobulin-fold
• Intracellular portion: wide variety of intracellular ligands, including:
o Signaling molecules
o Cytoskeletal proteins
• Most cadherins = single pass membrane glycoprotein
o 700-750 aa long
• Non-classical cadherins: wide variety of structures
• Others are anchored at the PM via GPI anchor (glycosylphosphatidylinositol)
o i.e. T-cadherin does not even have a TM domain (GPI anchor)
o Flamingo has many TM domains
o Some have kinase activity on intracellular side
• Directly involved in signalling into the cell (Ret)
• Some indirectly involved via adaptor proteins
Structure of Classical Cadherins
• Form dimers or large oligomers
• Large extracellular part is usually folded into 5-6 cadherin repeats (or more)
o Structurally related to Ig domains
