Hsp70/Hsp90 Organising Protein (Hop): Beyond Interactions with Chaperones and Prion Proteins - The Networking of Chaperones by Co-chaperones - page 73

Fig. 3.1 Structural domains and architecture of Hop proteins. a Three dimensional structure of
Hop domains. Images generated using Pymol (Delano Scientific). The PDB codes for the struc-
tures are: 3ESK for TPR1; 3UQ3 for TPR2AB; 2LLV for DP1; and 2LLW for DP2. b Comparison
of Hop domain structure across model organisms. TPR1: tetratricopeptide repeat domain 1; DP1:
aspartate-proline motif domain 1; TPR2AB: tetratricopeptide repeat domains 2A and B; DP2:
aspartate-proline motif domain 2. The N terminus is indicated by the number 1, while the numbers
at the C terminus gives the total number of amino acids in the proteins
Functions of Hop
The roles of Hop as a co-chaperone for Hsp70/Hsp90 complex and as a receptor for
the prion protein, PrP C , are the best described. However, there is a growing body of
literature that reports the involvement of Hop in cellular activities that appear inde-
pendent of either chaperones or PrP C (Table 3.1 ). However, it should be noted that
many of these studies do not demonstrate that Hsp70 or Hsp90 are not involved, but
rather fail to provide any evidence that they are involved. Therefore, it is possible