The P5 position refers to the amino acid residue that follows {HEAD ~ the amino acid residue} that occupies {TAIL ~ the P4 pocket} 
occupies
The P5 position refers to the amino acid residue that follows { HEAD ~ the amino acid residue } that occupies { TAIL ~ the P4 pocket }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL