Functionally distinct isoforms of dynactin are expressed in human neurons

被引:75
作者
Tokito, MK
Howland, DS
Lee, VMY
Holzbaur, ELF
机构
[1] UNIV PENN,SCH VET MED,DEPT ANIM BIOL,PHILADELPHIA,PA 19104
[2] CEPHALON INC,W CHESTER,PA 19380
[3] UNIV PENN,SCH MED,DEPT PATHOL & LAB MED,PHILADELPHIA,PA 19104
关键词
ACTIN-RELATED PROTEIN; MICROTUBULE-ASSOCIATED PROTEIN; RETROGRADE AXONAL-TRANSPORT; CYTOPLASMIC DYNEIN; DROSOPHILA-MELANOGASTER; MITOTIC SPINDLE; CELL-LINE; SACCHAROMYCES-CEREVISIAE; P150(GLUED) COMPONENT; SEQUENCE-ANALYSIS;
D O I
10.1091/mbc.7.8.1167
中图分类号
Q2 [细胞生物学];
学科分类号
071009 ; 090102 ;
摘要
p150(Glued) is the largest subunit of dynactin, which binds to cytoplasmic dynein and activates vesicle transport along microtubules. We have isolated human cDNAs encoding p150(Glued) as well as a 135-kDa isoform; these isoforms are expressed in human brain by alternative mRNA splicing of the human DCTN1 gene. The p135 isoform lacks the consensus microtubule-binding motif shared by members of the p150(Glued)/Glued/CLIP-170/BIK1 family of microtubule-associated proteins and, therefore, is predicted not to bind directly to microtubules. We used transient transfection assays and in vitro microtubule-binding assays to demonstrate that the p150 isoform binds to microtubules, but the p135 isoform does not. However, both isoforms bind to cytoplasmic dynein, and both partition similarly into cytosolic and membrane cellular fractions. Sequential immunoprecipitations with an isoform-specific antibody for p150 followed by a antibody revealed that, in brain, these polypeptides assemble to form distinct complexes, each of which sediments at similar to 20 S. On the basis of these observations, we hypothesize that there is a conserved neuronal function for a distinct form of the dynactin complex that cannot bind directly to cellular microtibules.
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页码:1167 / 1180
页数:14
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