Identification of major proteins in human cerebral cortex and brain tumors

Abstract

Two-dimensional gel electrophoresis (2DE) is being increasingly employed for protein separation, and silver staining has greatly enhanced its sensitivity. However, the identity of most of the protein spots demonstrated by 2DE has yet to be established. Using immunoblotting and comigration techniques, this study describes the identification of 12 of the major spots seen on 2D gels of normal human cerebral cortex and of certain human brain tumors. These proteins include: actin, albumin, α-tubulin, β-tubulin, neuron-specific enolase (NSE), nonneuronal enolase, glutamate oxaloacetic transaminase, glial fibrillary acidic protein (GFAP), vimentin, a 66-kD intermediate filament protein, the 68-kD neurofilament protein, and the β subunit of the guanine nucleotide regulatory proteins(G-proteins). In addition, the application of this technique to the study of human brain tumors has been described. A large amount of GFAP is seen in astrocytomas; the meningioma gel is characterized by a prominent vimentin complex; and the presence of NSE in medulloblastomas is confirmed. The identification of the β subunit of the G-proteins introduces a valuable means of screening for this important messenger protein, which is only beginning to be studied. While being derived from normal and pathological CNS tissue, these data are widely applicable to the study of other biological materials.