Involved in the export of the long day-specific flower-promoting signal (florigen) RFT1 from the phloem companion cells to sieve elements (PubMed:28254780). Promotes flowering under long days through the transport of RFT1 from the leaves to the shoot apical meristem (SAM) (PubMed:28254780). Interacts with RFT1 and PI4KG4. Specifically expressed in the phloem including companion cells. Delayed flowering phenotype under long day conditions. Belongs to the MCTP family. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus.