Has a role in establishing cell polarity. Together with cAMP-dependent protein kinase regulatory subunit BCY1, provides a negative feedback control on the cell wall integrity-signaling pathway by acting as a negative regulator of MAP kinase SLT2/MPK1. In heat-stressed cells appears to play a role in localizing BCY1 to the cytoplasm. Seems to interact with, and down-regulate, CDC42. Also acts as a suppressor of PKC1. May act as an integration point for distinct signaling pathways helping to maintain a balance among these different pathways. When associated with DBP5, GFD1 and nucleoporins at the cytosolic fibrils of the nuclear pore complex, is required for mRNA export form the nucleus. Interacts with BCY1, DBP5, GFD1 and SKG6. Concentrated at incipient bud site of unbudded cells and at the bud tip of small and medium-sized buds. 'ZDS' means 'zillion different screens' as both ZDS1 and ZDS2 have been found by a wide variety of genetic screens. Present with 279 molecules/cell in log phase SD medium. To yeast ZDS2/MCS1.