Resumen
[EN] We present the complete supersymmetric and κ-symmetric action for the 4-
dimensional interacting system of open supermembrane, dynamical supergravity and 3-
form matter multiplets. The cases of a single 3-form matter multiplet and a quite generic
model with a number of nonlinear interacting double 3-form multiplets are considered. In
all cases the fermionic parameter of the κ-symmetry is subject to two apparently different
projection conditions which suggests that the ground state of the system, in particular a
domain junction, might preserve at most 1/4 of the spacetime supersymmetry.
The boundary term of the open supermembrane action, needed to preserve the κ-
symmetry, has the meaning of the action of a superstring. The Wess-Zumino term of
this superstring action is expressed in terms of real linear superfield playing the role of
St¨uckelberg field for the 3-form gauge symmetry. This indicates that this symmetry is
broken spontaneously by the superstring at the boundary of supermembrane.