| Furthermore , GRG proteins interact with two regulators of GnRH transcription , the homeodomain proteins MSX 1 and OCT 1 . ^^^ The long GRG forms enhance MSX 1 repression and counteract OCT 1 activation of the GnRH gene . ^^^ In contrast , the short form , GRG 5 , has a dominant negative effect on MSX 1 dependent repression . ^^^ |