SPECIFIC INTERACTION OF THE RECOMBINANT DISINTEGRIN-LIKE DOMAIN OF MDC-15 (METARGIDIN, ADAM-15) WITH INTEGRIN ALPHA-V-BETA-3

MDC-15 (ADAM-15, metargidin), a membrane-anchored metalloprotease/disi ntegrin/cysteine-rich protein, is expressed on the surface of a wide r ange of cells and has an RGD tripeptide in its disintegrin-like domain , MDC-15 is potentially involved in cell-cell interactions through its interaction with integrins, We expressed a recombinant MDC-15 disinte grin-like domain as a fusion protein with glutathione S-transferase (d esignated D-15) in bacteria and examined its binding function to integ rins using mammalian cells expressing different recombinant integrins, We found that D-15 specifically interacts with alpha v beta 3 but not with the other integrins tested (alpha 2 beta 1, alpha 3 beta 1, alph a 4 beta 1, alpha 5 beta 1, alpha 6 beta 1, alpha 6 beta 4, alpha v be ta 1, alpha IIb beta 3, and alpha L beta 2). Mutation of the tripeptid e RGD to SGA totally blocked binding of D-15 to alpha v beta 3, sugges ting that D-15-alpha v beta 3 interaction is RGD-dependent. When the s equence <(RPT)under bar>RGD is mutated to <(NWK)under bar>RGD, D-15 is recognized by both alpha IIb beta 3 and alpha v beta 3, suggesting th at the receptor binding specificity is mediated by the sequence flanki ng the RGD tripeptide, as in snake venom disintegrins, These results i ndicate that the disintegrin-like domain of MDC-15 functions as an adh esion molecule and may be involved n alpha v beta 3-mediated cell cell interactions.