Plays an important role in meiotic recombination. Stimulates DMC1-mediated strand exchange required for pairing homologous chromosomes during meiosis. The complex PSMC3IP/MND1 binds DNA, stimulates the recombinase activity of DMC1 as well as DMC1 D-loop formation from double-strand DNA. This complex stabilizes presynaptic RAD51 and DMC1 filaments formed on single strand DNA to capture double-strand DNA. This complex stimulates both synaptic and presynaptic critical steps in RAD51 and DMC1-promoted homologous pairing. May inhibit HIV-1 viral protein TAT activity and modulate the activity of proteasomes through association with PSMC3. Acts as a tissue specific coactivator of hormone-dependent transcription mediated by nuclear receptors. Interacts with the DNA-binding domain of the nuclear receptors NR3C1/GR, ESR2/ER-beta, THRB and RXRA (By similarity). Forms a stable heterodimer with MND1. Interacts with PSMC3/TBP1. Highly expressed in testis and colon. Overexpressed in leiomyomas compared to myometrium. PTM: Phosphorylated by PKA, PKC and MAPK. The disease is caused by variants affecting the gene represented in this entry. Belongs to the HOP2 family.