Integrin alpha4beta1-dependent adhesion to ADAM 28 (MDC-L) requires an extended surface of the disintegrin domain

ADAMs (a disintegrin and metalloprotease) are a family of proteins that possess functional adhesive and proteolytic domains. ADAM 28 (MDC-L) is expressed by human lymphocytes and contains a disintegrin-like domain that serves as a ligand for the leukocyte integrin, alpha4beta1. To elucidate which re...

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Bibliographic Details
Published in:Biochemistry (Easton) 2003-04, Vol.42 (13), p.3734
Main Authors: Bridges, Lance C, Hanson, Krista R, Tani, Patricia H, Mather, Timothy, Bowditch, Ron D
Format: Article
Language:English
Subjects:
ADAM Proteins
Alanine - chemistry
Amino Acid Sequence
Amino Acid Substitution
Animals
Antibodies, Monoclonal - immunology
Binding Sites
Cell Adhesion
Disintegrins - chemistry
Disintegrins - metabolism
Epitope Mapping
Humans
Immunoglobulin Fc Fragments - immunology
Integrin alpha4beta1 - metabolism
Jurkat Cells
Lymphocytes - enzymology
Lymphoma, T-Cell - metabolism
Metalloendopeptidases - chemistry
Metalloendopeptidases - metabolism
Mice
Models, Molecular
Molecular Sequence Data
Mutagenesis, Site-Directed
Protein Conformation
Recombinant Proteins
Sequence Homology, Amino Acid
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Summary:ADAMs (a disintegrin and metalloprotease) are a family of proteins that possess functional adhesive and proteolytic domains. ADAM 28 (MDC-L) is expressed by human lymphocytes and contains a disintegrin-like domain that serves as a ligand for the leukocyte integrin, alpha4beta1. To elucidate which residues comprise the alpha4beta1 binding site in the ADAM 28 disintegrin domain, a charge-to-alanine mutagenesis strategy was utilized. Each alanine substitution mutant was evaluated and compared to the native sequence for its ability to support cell adhesion of the T-lymphoma cell line, Jurkat. This approach identified ADAM 28 residues Lys(437), Lys(442), Lys(455), Lys(459), Lys(460), Lys(469), and Glu(476) as being essential for alpha4beta1-dependent cell adhesion. The epitope for a function-blocking monoclonal antibody, Dis 1-1, was localized to the N-terminal end of the ADAM 28 disintegrin domain using these same charge-to-alanine mutants. Three distinct molecular models based upon the known structures of snake venom disintegrins suggested that residues contributing to alpha4beta1 recognition are aligned on one face of the domain. This study demonstrates that residues located outside of the disintegrin loop participate in integrin recognition of mammalian disintegrins.
ISSN:0006-2960