This effect of leucine arises results from its role as an activator of the mechanistic target of rapamycin ( mTOR ) , a serine-threonine protein kinase that regulates protein biosynthesis and cell growth .
DET NOUN ADP NOUN VERB NOUN ADP PRON NOUN ADP DET NOUN ADP DET ADJ NOUN ADP PROPN ( PROPN ) , DET ADJ NOUN NOUN DET VERB NOUN NOUN CCONJ NOUN NOUN .