D. Bigler et al., Sequence-specific interaction between the disintegrin domain of mouse ADAM2 (Fertilin beta) and murine eggs - Role of the alpha(6) integrin subunit, J BIOL CHEM, 275(16), 2000, pp. 11576-11584
Little is set known about the biological and biochemical properties of the
disintegrin-like domains of ADAM ((a) under bar (d) under bar isintegrin (a
) under bar nd (m) under bar etalloprotease) proteins. Mouse ADAM 2 2 (mADA
M 2; fertilin beta) is a sperm surface protein involved in murine fertiliza
tion. We produced recombinant proteins containing the disintegrin-like doma
in of mADAM 2 in both insect cells and in bacteria. The protein produced in
insect cells (baculo D+C) contained a signal sequence followed by the disi
ntegrin-like and cysteine-rich domains; it was purified from the medium of
recombinant baculovirus-infected cells. A bacterial construct containing th
e disintegrin-like domain was produced in Escherichia coli as a glutathione
S-transferase chimera. Baculo D+C, as well as the D domain of the bacteria
l construct (released with thrombin), bound to the microvillar surface of m
urine eggs. Using concentrations in the range of 1 to 5 mu m, both recombin
ant proteins strongly inhibited sperm-egg binding and fusion; the baculovir
us-produced protein exhibited a somewhat greater extent of inhibition (simi
lar to 75 versus similar to 55% maximal inhibition). Substitution of alanin
e for each of the five charged residues within the disintegrin loop of mADA
M 2 revealed a critical importance for the aspartic acid at position nine.
Binding of both recombinant proteins to the egg was inhibited by the functi
on blocking anti-alpha(6) monoclonal antibody, GoH3, but not by a nonfuncti
on-blocking anti-alpha(6) monoclonal antibody. Binding was also inhibited b
y a peptide analogue of, and with an antibody against, the disintegrin loop
of mADAM 2.