  In the physicist's language, a brane in a hyperkahler manifold is a
submanifold which is either complex or lagrangian with respect to three Kahler
structures of the ambient manifold. By considering the fixed loci of certain
involutions, we describe branes in Nakajima quiver varieties of all possible
types. We then focus on the moduli space of framed torsion free sheaves on the
projective plane, showing how the involutions considered act on sheaves, and
proving the existence of branes in some cases.
