If
complex mixtures are analyzed, a lot of information can be
obtained by a proper sample preparation and subsequent SDS-PAGE.
In Figure 2, difference between calcium binding proteins in
the plasma membranes of rat liver (left) and fast growing
Morris hepatoma 7777 is shown. These proteins have been identified
as annexins. Note the increased levels of annexins with lower
molecular weights (between 30 and 35 kDa) in the extract from
Morris hepatoma 7777 plasma membranes.
Figure
1
SDS-PAGE
of rat liver plasma membranes. Membrane proteins were
solubilized with 1% CHAPS in the absence of (left) or
presence of EDTA (right). Arrows - proteins which
are extracted after calcium complexing.
Left
– Buffer with 2 mM CaCl 2
Right
– Buffer with10 mM EDTA
Figure
2
SDS-PAGE
of calcium binding proteins (annexins) from plasma membranes
of rat liver (left) and Morris hepatoma 7777 (right).
Other
proteins have been removed by previous textraction with
1% Triton X100.
However,
2-D electrophoresis can yield much more information. As shown
in Figure 3, the two lower bands from the SDS-PAGE in Figure
2, contain more than 10 polypeptides with very similar molecular
weights that can be distinguished by differences in pI.
Figure
3
2-D electrophoresis
of calcium binding proteins (annexins) from plasma membranes
of Morris hepatoma 7777
