In the present study using mass-spectrometry we identify the sequence of the unique, junctional peptide contributed by the 5’ UTR of HspC ORF in the full length Hsp90 from Giardia lamblia. This peptide is critical for the catalytic function of Hsp90 as it harbours an essential “Arg” homolog in its sequence. We also show that full length GlHsp90 possesses all the functional hall marks of a canonical Hsp90 including its ability to bind and hydrolyze ATP.