Regulator of vesicle trafficking, including endocytosis. Necessary for secondary plasmodesmata (PD) formation and development via the secretory trafficking regulation of proteins required for PD development, thus influencing intercellular communication (PubMed:27743414, PubMed:29284002). Modulates ion homeostasis, especially in roots, by monitoring the transport and subsequent subcellular localization of some ion transporters (PubMed:29284002). Choline transporter involved in the regulation of choline metabolite homeostasis during root and phloem development (PubMed:25008948). Modulates phloem morphogenesis and conductivity (PubMed:25008948). Required for procambium maintenance and sieve plate development (e.g. sieve plate and sieve pore elaboration) to mediate long-distance cell-to-cell communication via symplastic transport through the phloem (PubMed:25008948). Involved in the regulation of intracellular trafficking of PIN-type auxin transporters (e.g. PIN1 and PIN3), a process controlling seedling growth, apical dominance, cell elongation and apical hook development. Modulates also membrane lipids (e.g. phospholipids and sphingolipids) homeostasis (PubMed:29283991). (Microbial infection) Required for PD localization of MP17, the luteoviral movement protein. Associated transiently with the phragmoplast during cytokinesis. Follows a polar localization in the forming sieve plates. Expressed in both roots and shoots. In roots, observed in all cells of the root tip, inculding both meristem and elongation zones, but restricted to vascular tissues of the maturation zone (PubMed:29284002, PubMed:29283991). Also observed in shoot apical meristems, lateral root primordia and the vascular system. Under dark conditions, present in the concave side of the apical hook (PubMed:29283991). Impaired plasmodesmata (PD) mediated cell-to-cell communication (PubMed:29284002). Altered choline metabolite profile. Several phenotypic abnormalities (e.g. dwarf with defects in both shoot and root architecture), including reduced pore density and altered pore structure in the sieve areas, associated with defective symplastic transport through phloem. Increased number of sieve elements (SE)-like cells instead of two companion cells (CCs) and two SEs. Defects in procambium maintenance and phloem patterning. Abnormal retaining of desmotubules in the symplastic space in sieve pores (PubMed:25008948). In cher1-4, impaired secondary plasmodesmata (PD) formation and development leading to starch and soluble sugars excess accumulation, and stunted growth. Altered PD localization of the luteoviral movement protein MP17. Reduced level of choline and phosphocholine (PubMed:27743414). Altered ion profile due to both PD defects and ion transporter misregulation. Increased leaf concentrations of sodium (Na), lithium (Li), boron (B) ions, and decreased leaf concentrations of phosphorus (P), potassium (K), calcium (Ca), cobalt (Co), nickel (Ni), and copper (Cu), manganese (Mn), iron (Fe), zinc (Zn) and molybdenum (Mo) ions. Defects in leaf and root elongation as well as fewer leaves are also observed, associated with irregular cell organization in roots, probably as a result of irregular cell division (PubMed:29284002). Impaired intracellular trafficking of PIN-type auxin transporters (e.g. PIN1 and PIN3) to the plasma membrane, resulting in abnormal seedling growth, lack of apical dominance, cell elongation defect and apical hook development. Perturbated membrane lipids (e.g. phospholipids and sphingolipids) homeostasis. Reduced sensitivity to auxin (e.g. 1-naphthylacetic acid, NAA) (PubMed:29283991). Belongs to the CTL (choline transporter-like) family.