Plays a role in the outgrowth of motoneurons and in the formation of neuromuscular junctions. Following muscle denervation, promotes nerve terminal sprouting and the formation of additional acetylcholine receptor clusters at synaptic sites without affecting terminal Schwann cell number or morphology. Delays the retraction of terminal sprouts following re-innervation of denervated endplates (By similarity). Plays a role in targeting the monocarboxylate transporters SLC16A1 and SLC16A7 to the cell membrane. Interacts with SLC16A1 and SLC16A7. Localizes to the neuromuscular junctions. Detected in prostate, mammary gland and erythrocytes (at protein level). Detected in testis, brain, prostate, heart, kidney, liver, mammary gland and lung. Regulated by muscle activity. Strongly up-regulated after muscle denervation, including that of soleus muscle. Expression is significantly increased 3 days after denervation and reaches a maximum, about 130-fold increase, after 5 days. N-glycosylated.