Thus, it could be speculated that, upon proteotoxic stress, HSF1 transactivating homocomplexes may be preferentially recruited to the distal elements, while HSF1/HSF2 heterocomplexes with repressing function are probably assembled on the proximal HSE. In addition, HSF2 exhibits two alternative splicing isoforms, at least in mice, one of which is able to reduce HSF1 activity by forming heterocomplexes with the HSF1β isoform under MG132 treatment [20 ].
Source: wiktionary