2. IDENTIFICATION OF HOMOLOGIES TO INTERNALIZATION
SIGNALS
An analysis of the PrP primary structure previously
identified a well conserved ‘aromatic palindrome’ region
(PrP:1477163 RYYRENMYRYPNQVYYR) containing
six of the 14 tyrosine residues in murine PrP [ 121.
Based on the topography of PrP [5], this region is located
mainly in the cytoplasmic (PrP: 1377155) domain.
Although the function of this region is not known, it
was suggested that it may act as a binding site for other
proteins [12]. The presence of conserved tyrosine residues
in this region, as well as in the adjacent region of
the cytoplasmic domain, prompted an analysis of structural
homologies to internalization signals.
Secondary structure analysis using the methods of
Chou and Fasman [13] and of Garnier et al. [ 141 predicted
a probability for turn structures at PrP:142 and
146, and in the region PrP:151-160. Based on thep-turn
structure exhibited by the model pentapeptide, YPNDV