scholarly journals Two Related Subpellicular Cytoskeleton-associated Proteins inTrypanosoma brucei Stabilize Microtubules

2002 ◽  
Vol 13 (3) ◽  
pp. 1058-1070 ◽  
Author(s):  
Cécile Vedrenne ◽  
Christiane Giroud ◽  
Derrick R. Robinson ◽  
Sébastien Besteiro ◽  
Christophe Bosc ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Molecular Weight ◽  
Trypanosoma Brucei ◽  
Cold Resistance ◽  
Chinese Hamster ◽  
Low Molecular Weight ◽  
Microtubule Bundle ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
Asymmetric Cytokinesis

The subpellicular microtubules of the trypanosome cytoskeleton are cross-linked to each other and the plasma membrane, creating a cage-like structure. We have isolated, from Trypanosoma brucei, two related low-molecular-weight cytoskeleton-associated proteins (15- and 17-kDa), called CAP15 and CAP17, which are differentially expressed during the life cycle. Immunolabeling shows a corset-like colocalization of both CAPs and tubulin. Western blot and electron microscope analyses show CAP15 and CAP17 labeling on detergent-extracted cytoskeletons. However, the localization of both proteins is restricted to the anterior, microtubule minus, and less dynamic half of the corset. CAP15 and CAP17 share properties of microtubule-associated proteins when expressed in heterologous cells (Chinese hamster ovary and HeLa), colocalization with their microtubules, induction of microtubule bundle formation, cold resistance, and insensitivity to nocodazole. When overexpressed inT. brucei, both CAP15 and CAP17 cover the whole subpellicular corset and induce morphological disorders, cell cycle-based abnormalities, and subsequent asymmetric cytokinesis.

scholarly journals A novel microtubule-binding motif identified in a high molecular weight microtubule-associated protein from Trypanosoma brucei

1992 ◽  
Vol 117 (1) ◽  
pp. 95-103 ◽  
Author(s):  
A Hemphill ◽  
M Affolter ◽  
T Seebeck
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Trypanosoma Brucei ◽  
Binding Motif ◽  
Amino Acid Repeat ◽  
Microtubule Binding ◽  
Microtubule Associated Proteins ◽  
Repeat Units ◽  
Associated Proteins

The major component of the cytoskeleton of the parasitic hemoflagellate Trypanosoma brucei is a membrane skeleton which consists of a single layer of tightly spaced microtubules. This array encloses the entire cell body, and it is apposed to, and connected with, the overlying cell membrane. The microtubules of this array contain numerous microtubule-associated proteins. Prominent among those is a family of high molecular weight, repetitive proteins which consist to a large extent of tandemly arranged 38-amino acid repeat units. The binding of one of these proteins, MARP-1, to microtubules has now been characterized in vitro and in vivo. MARP-1 binds to microtubules via tubulin domains other than the COOH-termini used by microtubule-associated proteins from mammalian brain, e.g., MAP2 or Tau. In vitro binding assays using recombinant protein, as well as transfection of mammalian cell lines, have established that the repetitive 38-amino acid repeat units represent a novel microtubule-binding motif. This motif is very similar in length to those of the mammalian microtubule-associated proteins Tau, MAP2, and MAP-U, but both its sequence and charge are different. The observation that the microtubule-binding motifs both of the neural and the trypanosomal proteins are of similar length may reflect the fact that both mediate binding to the same repetitive surface, the microtubule, while their sequence and charge differences are in agreement with the observation that they interact with different domains of the tubulins.

Microtubule motors and other maps

1990 ◽  
Vol 48 (3) ◽  
pp. 1-1
Author(s):  
Richard B. Vallee
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Cytoplasmic Dynein ◽  
Organelle Transport ◽  
Structural Components ◽  
Microtubule Associated Proteins ◽  
Microtubule Motors ◽  
Associated Proteins ◽  
The Subject ◽  
Intracellular Motility

Microtubules are involved in a number of forms of intracellular motility, including mitosis and bidirectional organelle transport. Purified microtubules from brain and other sources contain tubulin and a diversity of microtubule associated proteins (MAPs). Some of the high molecular weight MAPs - MAP 1A, 1B, 2A, and 2B - are long, fibrous molecules that serve as structural components of the cytamatrix. Three MAPs have recently been identified that show microtubule activated ATPase activity and produce force in association with microtubules. These proteins - kinesin, cytoplasmic dynein, and dynamin - are referred to as cytoplasmic motors. The latter two will be the subject of this talk.Cytoplasmic dynein was first identified as one of the high molecular weight brain MAPs, MAP 1C. It was determined to be structurally equivalent to ciliary and flagellar dynein, and to produce force toward the minus ends of microtubules, opposite to kinesin.

scholarly journals Identity and Origin of the ATPase activity associated with neuronal microtubules. I. The ATPase activity is associated with membrane vesicles.

1983 ◽  
Vol 96 (5) ◽  
pp. 1298-1305 ◽  
Author(s):  
D B Murphy ◽  
R R Hiebsch ◽  
K T Wallis
Keyword(s):  
Molecular Weight ◽  
Atpase Activity ◽  
High Molecular Weight ◽  
Brain Tissue ◽  
Membrane Vesicles ◽  
Microtubule Associated Proteins ◽  
In Vitro Assembly ◽  
Microtubule Protein ◽  
Associated Proteins

Microtubule protein purified from brain tissue by cycles of in vitro assembly-disassembly contains ATPase activity that has been postulated to be associated with microtubule-associated proteins (MAPs) and therefore significant for studies of microtubule-dependent motility. In this paper we demonstrate that greater than 90% of the ATPase activity is particulate in nature and may be derived from contaminating membrane vesicles. We also show that the MAPs (MAP-1, MAP-2, and tau factors) and other high molecular weight polypeptides do not contain significant amounts of ATPase activity. These findings do not support the concept of "brain dynein" or of MAPs with ATPase activity.

scholarly journals Association between endocrine pancreatic secretory granules and in-vitro-assembled microtubules is dependent upon microtubule-associated proteins.

1982 ◽  
Vol 93 (1) ◽  
pp. 164-174 ◽  
Author(s):  
K A Suprenant ◽  
W L Dentler
Keyword(s):  
Molecular Weight ◽  
Cyclic Amp ◽  
Light Microscopy ◽  
High Molecular Weight ◽  
Endocrine Pancreas ◽  
Secretory Granules ◽  
Dark Field ◽  
Microtubule Associated Proteins ◽  
Associated Proteins

By use of dark-field light microscopy, secretory granules isolated from the anglerfish endocrine pancreas were observed to attach to and release from microtubules assembled in vitro from brain homogenates. Secretory granules only bound to microtubules assembled in the presence of microtubule-associated proteins (MAPs) and not to microtubules assembled from purified tubulin. The addition of a MAP fraction to purified tubulin restored secretory granule binding. The secretory granules were released from MAP-containing microtubules by the addition of Mg-ATP but not by other nucleotides. The number of secretory granules bound to MAP-containing microtubules was increased in the presence of cyclic AMP. In addition to the associations of secretory granules with microtubules, MAP-containing microtubules also associated with each other. These laterally associated microtubules were dispersed by the addition of Mg-ATP. Electron micrographs confirmed that the associations between MAP-containing microtubules and secretory granules as well as the associations of microtubules with one another were mediated by the high molecular weight MAPs known to project from the surface of in-vitro-assembled microtubules.

scholarly journals Stable expression of heterologous microtubule-associated proteins (MAPs) in Chinese hamster ovary cells: evidence for differing roles of MAPs in microtubule organization.

1994 ◽  
Vol 126 (4) ◽  
pp. 1017-1029 ◽  
Author(s):  
S Barlow ◽  
M L Gonzalez-Garay ◽  
R R West ◽  
J B Olmsted ◽  
F Cabral
Keyword(s):  
Sodium Butyrate ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Constitutive Expression ◽  
Microtubule Assembly ◽  
Western Blots ◽  
Transfected Cells ◽  
Microtubule Associated Proteins ◽  
Associated Proteins

To study the effects of microtubule-associated proteins (MAPs) on in vivo microtubule assembly, cDNAs containing the complete coding sequences of a Drosophila 205-kD heat stable MAP, human MAP 4, and human tau were stably transfected into CHO cells. Constitutive expression of the transfected genes was low in most cases and had no obvious effects on the viability of the transfected cell lines. High levels of expression, as judged by Western blots, immunofluorescence, and Northern blots, could be induced by treating cells with sodium butyrate. High levels of MAPs were maintained for at least 24-48 h after removal of the sodium butyrate. Immunofluorescence analysis indicated that all three MAPs bound to cellular microtubules, but only the transfected tau caused a rearrangement of microtubules into bundles. Despite high levels of expression of these exogenous MAPs and the bundling of microtubules in cells expressing tau, transfected cells had normal levels of assembled and unassembled tubulin. With the exception of the tau-induced bundles, microtubules in transfected cells showed the same sensitivity as control cells to microtubule depolymerization by Colcemid. Further, all three MAPs were ineffective in reversing the taxol-dependent phenotype of a CHO mutant cell line. The absence of a quantitative effect of any of these heterologous proteins on the assembly of tubulin suggests that these MAPs may have different roles in vivo from those inferred previously from in vitro experiments.

A Low-Molecular-Weight Factor Extracted from Human Placenta Inhibits the Entry into Cell Cycle of Murine Pluripotent Stem Cells

1991 ◽  
Vol 628 (1 Negative Regu) ◽  
pp. 169-171
Author(s):  
M. LOPEZ ◽  
J. WDZIECZAK-BAKALA ◽  
PH. PRADELLES ◽  
V. BONY ◽  
E. FRINDEL
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Molecular Weight ◽  
Human Placenta ◽  
Pluripotent Stem Cells ◽  
Low Molecular Weight ◽  
Weight Factor
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