Jm. Boggs et al., Adhesion of acidic lipid vesicles by 21.5 kDa (recombinant) and 18.5 kDa isoforms of myelin basic protein, BBA-BIOMEMB, 1463(1), 2000, pp. 81-87
Myelin basic protein (MBP) is thought to be responsible for adhesion of the
intracellular surfaces of compact myelin to give the major dense line. The
17 and 21.5 kDa isoforms containing exon II have been reported by others t
o localize to the cytoplasm and nucleus of murine oligodendrocytes and HeLa
cells while the 14 and 18.5 kDa isoforms lacking exon II are confined to t
he plasma membrane, However, we show that the exon II- 18.5 kDa form and a
recombinant exon II+ 21.5 kDa isoform both caused similar aggregation of ac
idic lipid vesicles, indicating that they should have similar abilities to
bind to the intracellular lipid surface of the plasma membrane and to cause
adhesion of those surfaces to each other. The circular dichroism spectra o
f the two isoforms indicated that both had a similar secondary structure. T
hus, both isoforms should be able to bind to and cause adhesion of the cyto
solic surfaces of compact myelin. The fact that they do not could be due to
differences in post-translational modification in vivo, trafficking throug
h the cell and/or subcellular location of synthesis, but it is not due to d
ifferences in their lipid binding. (C) 2000 Elsevier Science B.V. All right
s reserved.