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A combination of posttranslational modifications is responsible for the production of neuronal α‐tubulin heterogeneity
Author(s) -
Eddé Bernard,
Rossier Jean,
Caer JeanPierre Le,
BerwaldNetter Yoheved,
Koulakoff Annette,
Gros François,
Denoulet Philippe
Publication year - 1991
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.240460207
Subject(s) - acetylation , tubulin , microtubule , gene isoform , isoelectric focusing , biochemistry , isoelectric point , biology , peptide , chemistry , enzyme , microbiology and biotechnology , gene
We describe the presence of α‐tubulin and MAP2 acetyltransferase activities in mouse brain. The enzyme(s) copurified with microtubules through two cycles of assembly‐disassembly. Incubation of microtubule proteins with [ 3 H]acetyl CoA resulted in a strong labeling of both α‐tubulin and MAP2. To determine the site of the modification, tubulin was purified and digested with Glu‐C endoproteinase. A unique radioactive peptide was detected and purified by HPLC. Edman degradation sequencing showed that this peptide contained € N ‐acetyllysine at position 40 of the α‐tubulin molecule. This result demonstrates that mouse brain α‐tubulin was acetylated at the same site as in Chlamydomonas . Isoelectric focusing analysis showed that acetylated α‐tublin was resolved into five isoelectric variants, denoted α3 and α5 to α8. This heterogeneity is not due to acetylation of other sites but results from a single acetylation of Lys 40 of an heterogeneous population of α‐tubulin isoforms. These isoforms are produced by posttranslational addition of one to five glutamyl units. Thus, neuronal α‐tubulin is extensively modified by a combination of modifications including acetylation, glutamylation, tyrosylation, and other yet unknown modifications.