The invention also relates to DNA constructs encoding the variants, and to vectors and {HEAD ~ cells} harboring {TAIL ~ the DNA constructs} 
harboring
The invention also relates to DNA constructs encoding the variants , and to vectors and { HEAD ~ cells } harboring { TAIL ~ the DNA constructs }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL