Its central MAP kinase module was subject of diverse studies and is conserved from Saccharomyces cerevisiae to filamentous fungi, such as Aspergillus spp.. On the contrary, components upstream of this MAP kinase module are well characterized in S. cerevisiae but largely unknown in Aspergillus spp.. We have identified, localized and functionally characterized homologues of the S. cerevisiae cell surface sensors ScWsc1 -ScWsc3 and ScMid2/ScMtl1 in A. fumigatus.