MSB2 and SHO1 have overlapping functions in recognizing various surface signals for MAPK PMK1 activation and appressorium formation (PubMed:21283781). While MSB2 is critical for sensing surface hydrophobicity and cutin monomers, SHO1 may play a more important role in recognizing rice leaf waxes (PubMed:21283781). During conidium germination and appressorium formation, localizes at the cell membrane and in vacuoles (PubMed:21283781). In mature appressoria, mainly localized to vacuole-like structures (PubMed:21283781). Expression is significantly reduced when PMK1 or MST12 are disrupted. The extracellular serine/threonine rich region (STR) and the HKR11-MSB2 homology domain (HMH) are essential for MBS2 function, whereas the C-terminal cytoplasmic tail is dispensable for appressorium formation and virulence. Reduces significantly appressorium formation and virulence. Belongs to the HKR1/MSB2 family.