Plasma membrane osmosensor that activates the high osmolarity glycerol (HOG) MAPK signaling pathway in response to high osmolarity. Detects changes in external osmolarity and activates PBS2 through the stimulation of STE11 and targets PBS2 to the plasma membrane. PBS2 activation leads to changes in glycerol production that helps to balance the intracellular and external osmotic pressures. Activates also HOG1 in response to heat stress and mediates resistance to oxidative stress. Involved in the regulation of the mating pathway. May be a receptor that feeds into the pseudohyphal growth pathway (By similarity). Forms homooligomers (By similarity). Interacts (via the SH3 domain) with PBS2. Interacts with FUS1, STE11, STE50 and RNA polymerase II (By similarity). Localizes at the tip of the mating projection during conjugation. Belongs to the SHO1 family.