Myelin Basic Protein, A Saucy Molecule With High Responsiveness to the Environment or Just an Unusual Membrane Protein? - Molecules: Nucleation, Aggregation and Crystallization - page 179

1982; Smith, 1992; Staugaitis et al ., 1996; Riccio et al ., 2000), and that
both components work synergistically to provide the adhesion and overall
structure (Hu et al ., 2004).
In the 1980s, we introduced the idea that, if MBP is a membrane pro-
tein, it should be extracted with detergents and not with strong acids.
Furthermore, we suggested that MBP should be extracted directly from
myelin and not from whole brain.
Following the treatment of myelin with mild detergents, MBP was
extracted together with its natural lipid environment. Purified MBP was
found to be associated to almost all myelin lipids and was called lipid-
bound MBP (LB-MBP) (Riccio et al ., 1984). MBP extracted with the
detergent CHAPS was found to be associated mainly with phosphoglyc-
erides (Riccio et al ., 1994). After the discovery of myelin rafts, it was
clear that the CHAPS-extracted LB-MBP was MBP present in the non-raft
region of myelin.
LB-MBP was found to differ in various structural and immunological
aspects from the LF-MBP (Bobba et al ., 1991; Lolli et al ., 1993;
Massacesi et al ., 1993; Liuzzi et al ., 1996; Vergelli et al ., 1997; Mazzanti
et al ., 1998). Circular dichroism measurements showed that LB-MBP has
a much higher proportion of ordered secondary structure than LF-MBP,
which was a substantially random coil protein (Polverini et al ., 1999).
Small angle X-ray scattering (SAXS) studies on LB-MBP in solution con-
firmed the CD studies (Haas et al ., 2004). According to the results
obtained with CD and SAXS measurements, the structural model of
Beniac et al . (1997) and Ridsdale et al . (1997) was modified. The
Beniac-Ridsdale model of the human MBP in the presence of lipids (entry
1qcl in the Protein Data Bank), built up using both experimental (electron
microscopy) and computational techniques, was a C-shaped structure. The
main differences between our model and the 1qcl model are represented
by the replacement of two coil segments (residues 61-66 and 131-136),
which lie at the two ends of the C-shaped model with α -helical structures,

although the characteristic C-shape is maintained.
With LB-MBP and lipids, self-organization of stable, myelin-like
membranes could be induced under conditions in which lipids alone