Premium
Multiple Forms of the 26S Proteasome‐Associated Protein Ecm29 in the Mouse Brain
Author(s) -
Gorbea Carlos,
Kaufmann Anthony G.,
Pratt Gregory,
Rechsteiner Martin,
Rogers Scott W.
Publication year - 2006
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1560/742p-et1j-8rlc-2jyv
Subject(s) - gene isoform , chemistry , proteasome , polyclonal antibodies , alternative splicing , antibody , immunohistochemistry , central nervous system , protein splicing , yeast , homogenization (climate) , microbiology and biotechnology , biochemistry , gene , neuroscience , biology , genetics , immunology , biodiversity , ecology
Ecm29 is an ˜200‐K HEAT‐repeat protein that associates with the 26S proteasome in yeast and HeLa cells. Whereas in most mouse organs Ecm29 is present as a single 200‐K protein, in the brain there are eleven species, ranging from 55 K to greater than 250 K, that react with anti‐Ecm29 antibodies. Since the largest brain‐specific Ecm29 variant reacts with antibodies to sequences within the N‐terminal and C‐terminal regions of the protein, but not to the antibody directed to its central region, this putative isoform likely arises by alternative splicing. Some of the smaller Ecm29‐positive forms appear to arise by proteolytic processing, but extraction of minced brain fragments in boiling SDS‐PAGE sample buffer reveals that all forms are present prior to homogenization. Only the 220‐K Ecm29 species is clearly associated with the 26S proteasome; with one exception, the other variants sediment slower than 20S. Direct dissection and immunohistochemistry reveal that these putative Ecm29 isoforms are present throughout the central nervous system. However, anti‐Ecm29 immunoreactivity is differentially distributed within subregions of the mouse brain and among cell types, suggesting that Ecm29 isoform distribution contributes to the complexity and regional specificity of brain function.