Involved in the glucose-triggered developmental leaf growth process. Expressed in the vasculature of leaves, roots, inflorescences, siliques, anther filaments and sepals. Detected primarily in the phloem tissues, including in the root ans shoot apical meristems. Up-regulated by glucose (Ref.6). Down-regulated by STKL1 and STKL2 (PubMed:27031427). Belongs to the TMEM19 family.