Hypothetical model showing the targeting of the secreted PdAPs into the cytoplasmic sleeve. Schematic representation of PDLP5 vesicular transport involving specific t18:0-based sphingolipid traffic with the final destination in the Pd cavity. Formins are hypothesized to be delivered to the Pd in a similar way. C1RGP is secreted to the cell wall and reaches its location in the Pd cytoplasmic sleeve by an unknown mechanism. Sphingolipids are designated as purple rods. CW, cell wall; C1RGP, Class 1 reversibly glycosylated polypeptide; DT, desmotubule; GA, the Golgi apparatus; PDLP5, Pd-located protein 5.