Sterol regulatory element binding proteins (SREBPs) are transcription factors that are conserved from yeast to humans. In mammals they regulate cholesterol synthesis, in fungi they are additionally involved in hypoxic response (Sre1 in Schizosaccharomyces pombe), resistance to azole compounds (Sre1 in Cryptococcus neoformans), and pathogenesis (SrbA in Aspergillus fumigatus), among others. More recent studies also reveal the role of SREBP Sah2 in protein secretion in Neurospora crassa. Typically, the N-terminus of SREBPs harbors the transcription factor domain, which is a basic-helix-loop-helix leucine zipper (bHLH-LZ) structure. Thereby, the leucine zipper allows for dimerization. Structure analysis of Sah2 of Trichoderma ressei revealed, that its bHLH-LZ is highly similar to the C-terminal bHLH-LZ of transcription factor Xpp1.Our recent work elucidated the critical role of Xpp1 in the metabolism of T. reesei. When Xpp1 is deleted, growth is impaired and the expression of sorbicillinoids and low weight molecules is increased. Those findings support the conclusions from RNA-Seq results, that Xpp1 activates primary metabolism, however, it represses secondary metabolism. In this work, we investigated the interaction between Sah2 and Xpp1 in order to regulate metabolic processes in T. reesei. Different imaging techniques were used to observe the co-localisation of the fluorescence-tagged molecules inside the cell. Additionally, we analyzed different metabolic processes and their dependencies from the presence of either transcription factor.