Plasmodesmal-associated protein kinase 1 (PAPK1) is an Arabidopsis homolog of plasmodesmal-associated protein kinase, which was identified from plasmodesmal enriched cell wall proteins of Nicotiana tobaccum (Lee et al., 2003). PAPK1 was found to phosphorylate a number of non-cell autonomous proteins and to colocalize with the movement protein of tobacco mosaic virus, forming punctate speckles around the periphery of cells (Lee et al., 2005). Since PAPK1 has a distinctive localization pattern, we hypothesize that this localization pattern is essential for its function and, therefore, mutations that alter this localization will be in a gene involved in PAPK1 targeting. To test this, a line of plants which over-express PAPK1 was mutagenized with ethylmethane sulfonate to screen for putative PAPK1 effector mutants. Several mutants exhibiting mislocalization patterns were found, including one in which the PAPK1 vesicle like structures were aggregated together within the cell, which was referred to as vesicle condensation. This mutation was found to be recessive and result in plants which were dwarfed, had unsymmetrical leaves, and flowered early. Rough mapping showed the mutation to be located between 6.4 and 12.9Mb on chromosome 2. Two models are proposed, one in which a microtubule biding protein is mutated and one in which an actin binding protein is mutated, both suggesting that the PAPK1 speckles can form but their bulk movement along the actin is blocked, thus forcing them to condense within the cytoplasm. Ongoing work has also suggested that the mutated gene may be clathrin or μ2, which are involved in vesicle trafficking.