Identification of alpha-dystroglycan binding sequences in the laminin alpha2 chain LG4-5 module.
The biological activities of the laminin alpha2 chain LG4-5 module result from interactions with cell surface receptors, such as heparan sulfate proteoglycans and alpha-dystroglycan. In this study, heparin and alpha-dystroglycan binding sequences were identified using 42 overlapping synthetic peptides from the LG4-5 module and using recombinant LG4-5 protein (rec-alpha2LG4-5). Physiological activities of the active peptides were also examined in explants of submandibular glands. Heparin binding screens showed that the A2G78 peptide (GLLFYMARINHA) bound to heparin and prevented its binding to rec-alpha2LG4-5. Furthermore, alanine substitution of the arginine residue in the A2G78 site on rec-alpha2LG4-5 decreased heparin binding activity. When alpha-dystroglycan binding of the peptides was screened, two peptides, A2G78 and A2G80 (VQLRNGFPYFSY), bound alpha-dystroglycan. A2G78 and A2G80 also inhibited alpha-dystroglycan binding of rec-alpha2LG4-5. A2G78 and A2G80 specifically inhibited end bud formation of submandibular glands in culture. These results suggest that the A2G78 and A2G80 sites play functional roles as heparan sulfate- and alpha-dystroglycan-binding sites in the module. These peptides are useful for elucidating molecular mechanisms of heparan sulfate- and/or alpha-dystroglycan-mediated biological functions of the laminin alpha2 chain.
Suzuki
Nobuharu
N
Laboratory of Clinical Biochemistry, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan.
Hozumi
Kentaro
K
Urushibata
Shunsuke
S
Yoshimura
Takashi
T
Kikkawa
Yamato
Y
Gumerson
Jessica D
JD
Michele
Daniel E
DE
Hoffman
Matthew P
MP
Yamada
Yoshihiko
Y
Nomizu
Motoyoshi
M
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D004252:DNA Mutational Analysis; D049030:Dystroglycans / Q000235:genetics / Q000378:metabolism*; D006493:Heparin / Q000378:metabolism; D006801:Humans; D007797:Laminin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009024:Morphogenesis / Q000502:physiology; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013363:Submandibular Gland / Q000033:anatomy & histology / Q000502:physiology
D007797:Laminin; D010455:Peptides; D011994:Recombinant Proteins; C102645:laminin alpha 2; D049030:Dystroglycans; D006493:Heparin