Essential protein which may play a role in mitochondrial morphogenesis and function. Has transfer RNA (tRNA)-binding activity and can bind tRNA(Ser) but does not have serine--tRNA ligase activity and does not bind ATP. Expressed from late embryogenesis with expression continuing in larva, pupa and adult (at protein level). Belongs to the class-II aminoacyl-tRNA synthetase family. Type-1 seryl-tRNA synthetase subfamily.