The C-terminus of the gamma 2 chain but not of the beta 3 chain of laminin-332 is indirectly but indispensably necessary for integrin-mediated cell reactions.
Using a recombinant mini-laminin-332, we showed that truncation of the three C-terminal amino acids of the gamma 2 chain, but not of the C-terminal amino acid of the beta 3 chain, completely abolished alpha 3 beta 1 integrin binding and its cellular functions, such as attachment and spreading. However, a synthetic peptide mimicking the gamma 2 chain C-terminus did not interfere with alpha 3 beta 1 integrin binding or cell adhesion and spreading on laminin-332 as measured by protein interaction assays and electric cell-substrate impedance sensing. Nor was the soluble peptide able to restore the loss of integrin-mediated cell adhesiveness to mini-laminin-332 after deletion of the gamma 2 chain C-terminus. These findings spoke against the hypothesis that the gamma 2 chain C-terminus of laminin-332 is a part of the alpha 3 beta 1 integrin interaction site. In addition, structural studies with electron microscopy showed that truncation of the gamma 2 chain C-terminus opened up the compact supradomain structure of LG1-3 domains. Thus, by inducing or stabilizing an integrin binding-competent conformation or array of the LG1-3 domains, the gamma 2 chain C-terminus plays an indirect but essential role in laminin-332 recognition by alpha 3 beta 1 integrin and, hence, its cellular functions.
Institute for Physiological Chemistry, Muenster University Hospital, 48149 Muenster, Germany.
Alexei
A
Navdaev
Vanessa
V
Heitmann
Karla
K
Desantana Evangelista
Matthias
M
Mörgelin
Joachim
J
Wegener
Johannes A
JA
Eble
D000595:Amino Acid Sequence / Q000502:physiology; D000818:Animals; D001485:Basement Membrane / Q000378:metabolism* / Q000648:ultrastructure; D001665:Binding Sites / Q000502:physiology; D002448:Cell Adhesion / Q000502:physiology; D015815:Cell Adhesion Molecules / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D002465:Cell Movement / Q000502:physiology; D004847:Epithelial Cells / Q000378:metabolism* / Q000648:ultrastructure; D039201:Integrin alpha3beta1 / Q000737:chemistry / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000097794:Kalinin
D015815:Cell Adhesion Molecules; D039201:Integrin alpha3beta1; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; D000097794:Kalinin