To determine whether the tag itself was potentially causing a defect in Abp1 function, the uptake of Lucifer yellow was analysed in cells expressing the C-terminally tagged Abp1 proteins. As shown both tagged proteins caused a defect in fluid phase uptake in the control cells indicating a dominant effect of the tag on normal endocytic function. In the presence of Lat-A, wild type cells showed reduced trafficking with about 20% of cells observed to traffic Lucifer yellow to the vacuole, the rest of the cells having endosomal staining. This level of uptake was mirrored in the Abp1-mRFP tagged cells, but not in the cells carrying Abp1-GFP indicating that the mRFP tagged Abp1 is able to function within this endocytic pathway despite not showing OTX015 moa strong localization to endocytic punctae. In this work we have investigated the uptake of bulk fluid and lipid which is able to enter cells even when the classical endocytic pathway is inhibited. Analysis of FM4-64 uptake in cells also expressing Sla1-GFP in wild type cells, revealed that this uptake can take place at distinct sites from one another. In addition, in budded cells FM4-64 can be observed to internalize in the mother and bud of cells while Sla1-GFP localizes mostly in the bud. FM464 uptake appears more diffuse than the puncta observed for the endocytic reporters such as Sla1-GFP, though the reason for this is not yet clear. Given that FM4-64 is found only in the endomembrane system and not in other membrane trafficking compartments this indicates that entry is likely to be mediated through some kind of vesicular carrier which then fuses with endosomes. It is important to note that even this uptake is inhibited with high levels of Lat-A indicating that it is still an actin mediated process. Addition of low levels of Lat-A was shown to disrupt the normal CME route of endocytosis but not to cause disassembly of cortical F-actin structures nor to inhibit bulk endocytic uptake of fluid or lipid judged by uptake of the dyes Lucifer yellow or FM4-64. Under these conditions, both the endocytic reporter Sla1-GFP and the cargo GFP-Snc1 were inhibited in uptake. Analysis of proteins required when the classical route of endocytosis was inhibited reveal an Abp1-dependent endocytic pathway. This function of Abp1 requires both its SH3 domain and its acidic regions which have been reported to interact with Arp2/3. Interestingly, a deletion of the gene encoding the kinase Ark1 but not the related Prk1, phenocopies the abp1 deletion indicating a distinct/non-overlapping function for the Ark1 kinase.