Together with BOLA2, acts as a cytosolic iron-sulfur (Fe-S) cluster assembly factor that facilitates [2Fe-2S] cluster insertion into a subset of cytosolic proteins (By similarity). Acts as a critical negative regulator of cardiac hypertrophy and a positive inotropic regulator (By similarity). Required for hemoglobin maturation. Does not possess any thyoredoxin activity since it lacks the conserved motif that is essential for catalytic activity (By similarity). Homodimer; the homodimer is independent of 2Fe-2S clusters. Heterotrimer; forms a heterotrimeric complex composed by two BOLA2 molecules and one GLRX3 molecule; linked by [2Fe-2S] clusters. Interacts (via N-terminus) with PRKCQ/PKC-theta (By similarity). Interacts (via C-terminus) with CSRP3 (By similarity). Interacts with CSRP2 (By similarity). Under the plasma membrane (By similarity). After PMA stimulation, GLRX3 and PRKCQ/PKC-theta translocate to a more extended submembrane area (By similarity). In the Z line, found associated with CSRP3 (By similarity). The thioredoxin domain lacks the two redox-active cysteines. This strongly suggests that it lacks thioredoxin activity.