  We derive the vertex operators that are expected to govern the emission of
the massless d=11 supermultiplet from the supermembrane in the light cone
gauge. We demonstrate that they form a representation of the supersymmetry
algebra and reduce to the type IIA superstring vertex operators under double
dimensional reduction, as well as to the vertices of the d=11 superparticle in
the point-particle limit. As a byproduct, our results can be used to derive the
corresponding vertex operators for matrix theory and to describe its linear
coupling to an arbitrary d=11 supergravity background. Possible applications
are discussed.
