Tn552 transposase catalyzes concerted strand transfer in vitro

MDC-15 (ADAM-15, metargidin), a membrane-anchored metalloprotease/disintegrin/cysteine-rich protein, is expressed on the surface of a wide range 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 disintegrin-like domain as a fusion protein with glutathione S-transferase (designated D-15) in bacteria and examined its binding function to integrins using mammalian cells expressing different recombinant integrins. We found that D-15 specifically interacts with alphavbeta3 but not with the other integrins tested (alpha2beta1, alpha3beta1, alpha4beta1, alpha5beta1, alpha6beta1, alpha6beta4, alphavbeta1, alphaIIbbeta3, and alphaLbeta2). Mutation of the tripeptide RGD to SGA totally blocked binding of D-15 to alphavbeta3, suggesting that D-15-alphavbeta3 interaction is RGD-dependent. When the sequence RPTRGD is mutated to NWKRGD, D-15 is recognized by both alphaIIbbeta3 and alphavbeta3, suggesting that the receptor binding specificity is mediated by the sequence flanking the RGD tripeptide, as in snake venom disintegrins. These results indicate that the disintegrin-like domain of MDC-15 functions as an adhesion molecule and may be involved n alphavbeta3-mediated cell-cell interactions.