Regulator of microtubule required for axonal extension during embryonic development (PubMed:27422099). Promotes microtubule bundling and polymerization (PubMed:27422099). Together with futsch, required for neuromuscular junction (NMJ) bouton growth by regulating synaptic microtubules (PubMed:31156389). Found in a complex with tubulin and Futsch. Localizes at the presynaptic neuromuscular junction (NMJ). Highly expressed in adult head (at protein level). Mainly expressed in neurons and later in midline glia during ventral nerve cord (VNC) development (at protein level). Embryonic nervous system defects characterized by cell misplacement and errors in axonal extension and targeting (PubMed:27422099). Neurons display defective axonal extension (PubMed:27422099). Defects are probably caused by impaired microtubule organization and integrity (PubMed:27422099). During larval neuromuscular junction (NMJ) synaptic development, larvae show reduced synaptic growth and transmission (PubMed:31156389). Flies lacking both Ringer and Futsch display a significant reduction in microtubule loops at the neuromuscular junctions (NMJ) and reduced acetylated-tubulin levels (PubMed:31156389). Belongs to the TPPP family.