The PPFLMLLKGSTR motif in globular domain 3 of the human laminin-5 alpha3 chain is crucial for integrin alpha3beta1 binding and cell adhesion.
Laminin-5 regulates various cellular functions, including cell adhesion, spreading, and motility. Here, we expressed the five human laminin alpha3 chain globular (LG) domains as monomeric, soluble fusion proteins, and examined their biological functions and signaling. Recombinant LG3 (rLG3) protein, unlike rLG1, rLG2, rLG4, and rLG5, played roles in cell adhesion, spreading, and integrin alpha3beta1 binding. More significantly, we identified a novel motif (PPFLMLLKGSTR) in the LG3 domain that is crucial for these responses. Studies with the synthetic peptides delineated the PPFLMLLKGSTR peptide within LG3 domain as a major site for both integrin alpha3beta1 binding and cell adhesion. Substitution mutation experiments suggest that the Arg residue is important for these activities. rLG3 protein- and PPFLMLLKGSTR peptide-induced keratinocyte adhesion triggered cell signaling through FAK phosphorylation at tyrosine-397 and -577. To our knowledge, this is the first report demonstrating that the PPFLMLLKGSTR peptide within the LG3 domain is a novel motif that is capable of supporting integrin alpha3beta1-dependent cell adhesion and spreading.
Kim
Jin-Man
JM
Department of Oral Biochemistry and Craniomaxillofacial Reconstructive Sciences, Dental Research Institute, IBEC, and BK21 HLS, Seoul National University College of Dentistry, 28 Yeonkun-Dong, Chongno-Ku, Seoul 110-749, Korea.
Park
Won Ho
WH
Min
Byung-Moo
BM
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D002448:Cell Adhesion; D002460:Cell Line; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D039201:Integrin alpha3beta1 / Q000378:metabolism*; D007797:Laminin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction
D039201:Integrin alpha3beta1; D007797:Laminin; D011994:Recombinant Proteins; C095567:laminin alpha 3; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human