Actin interacts with many associated proteins that regulate its arrangement, organization and function. In filamentous fungi, F-actin has been found in the Spitzenkörper (Spk), an area at the apical cytoplasm adjacent to the growth site, as well as in cortical actin patches and cables in the subapex. The functions of these various F-actin arrangements are still not clear. By analogy, actin in the Spk has been proposed as a regulator of vesicle delivery and/or fusion at the growing plasma membrane (exocytosis). Similarly, cortical actin patches have been proposed to play a role in endocytosis (plasma membrane invagination). We have described the localization and partially the dynamics of some Actin Binding Proteins (ABPs) such as fimbrin, Arp2/Arp3, coronin, tropomyosin and actin itself in Neurospora crassa. This study will be focused on the interaction of actin, ABPs and actin-related motor proteins during the process of endocytosis, exocytosis and vesicle trafficking in N. crassa. We will examine the temporal and spatial relation between these proteins by co-immunoprecipitation to determine the physical interaction between them and the components of vesicles related to endo and exocytosis. In order to understand the function of the ABPs and myosin we will analyze the behavior of their corresponding mutants.
Figure 1. Apical distribution of ABPs in N. crassa
Figure 2. ABPs in developing septa