Involved in the export of FT from the phloem companion cells to the sieve elements through the plasmodesmata. Regulates flowering time under long days. Interacts with FT in phloem companion cells. Localized in plasmodesmata between companion cells and sieve elements. Expressed in the vascular tissues of cotyledons and rosette leaves. Specifically located in the phloem including companion cells. Not detected in the shoot apical meristem. Up-regulated by APL/FE (PubMed:26239308). Not regulated by photoperiod, circadian rhythm under long days, vernalization or gibberellin treatment (PubMed:22529749). Late flowering under long days. Unlike other flowering promoters, overexpression of FTIP1 causes late flowering due to the deregulation of FT transport out of the phloem system. Belongs to the MCTP family.