We present the superfield action for the dynamical N=1 D=4 supermembrane in
interaction with a dynamical scalar multiplet and use it to derive the
superfield equations of motion. These include the supermembrane equations,
which formally coincide with equations of supermembrane in a background of the
(off-shell) scalar multiplet, and the special chiral superfield equations with
supermembrane source. In the case when the scalar supermultiplet part of the
action contains only the simplest kinetic term we have also extracted the
spacetime component field equations from the superfield equations and solve
these in the leading order on supermembrane tension. The inclusion of
nontrivial superpotential and relation with known supersymmetric domain wall
solutions is briefly discussed.Comment: 26 pages. V2: misprints corrected, references and an acknowledgment
added, minor changes, in particular in sec. 4.2.1. V.3. discussion on the
relation with known solutions added; to appear in Nucl.Phys. B (2011