Characterization of postmortem XXXX brain proteins by two-dimensional gel electrophoresis.

@entity1 @entity575 @entity4482 @entity35 @entity204
The proteins of membrane and cytosol fractions from frozen @entity1 postmortem brain were analyzed by two-dimensional gel electrophoresis (isoelectric range: 5.1-6.0) and both @entity4482 and ammoniacal @entity575 staining. Cytosol preparations were analyzed from six different postmortem brains from @entity1 with various neurologic diagnoses and immediate causes of @entity204 . Intervals between @entity204 and brain freezing (-70 degrees C) ranged from 2 to 20 h. The vast majority of proteins detected in these cytosol fractions had identical molecular weights and isoelectric points in each of six @entity1 brains examined. However, in some tissue samples tubulin was either quantitatively decreased or undetectable. The possibility that this partial or complete depletion of tubulin was related to postmortem interval and/or brain freezing was studied using @entity35 forebrain tissue. @entity35 brain incubated at room temperature for up to 24 h did not reproduce the changes seen in the region of @entity1 cytosol tubulin. However, other changes seen in the two-dimensional electrophoretic pattern of @entity35 cytosol proteins did relate to postmortem interval, brain freezing, or both. Rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum were prepared from three @entity1 brains, with highly reproducible two-dimensional patterns. Protein analysis of these membrane fractions revealed that @entity1 RER contained significant amounts of tubulin, in contrast to @entity35 RER which contained no detectable tubulin. This discrepancy was elucidated by allowing @entity35 brains to remain at room temperature for 24 h before freezing; gels of @entity35 RER prepared from this tissue showed that tubulin subunits were present.
