Formation and function of the Rbl2p-beta-tubulin complex
J E Archer1, M Magendantz, L R Vega
1Department of Biology and Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139, USA.
Molecular and Cellular Biology
|March 6, 1998
Summary
The yeast protein Rbl2p binds beta-tubulin, forming a distinct cellular pool. This interaction regulates beta-tubulin levels and dimerization, impacting cell function.
Area of Science:
- Cell Biology
- Molecular Biology
- Protein Interactions
Background:
- Tubulin dynamics are crucial for cell function.
- Alpha- and beta-tubulin form heterodimers essential for microtubule assembly.
- Regulation of free tubulin subunits is critical for maintaining cellular homeostasis.
Purpose of the Study:
- To investigate the role of yeast protein Rbl2p in regulating beta-tubulin.
- To characterize the interaction between Rbl2p and beta-tubulin.
- To understand how Rbl2p affects tubulin homeostasis and cellular function.
Main Methods:
- In vivo and in vitro complex formation assays.
- Analysis of Rbl2p-beta-tubulin complex stability and half-life.
- Studies on the effect of Rbl2p on cells overexpressing beta-tubulin.
Main Results:
- Rbl2p efficiently suppresses excess beta-tubulin effects.
- Rbl2p forms a distinct Rbl2p-beta-tubulin complex independent of alpha-tubulin.
- Newly synthesized beta-tubulin preferentially binds Rbl2p over alpha-tubulin.
- The Rbl2p-beta-tubulin complex is less stable than the alpha/beta-tubulin heterodimer.
Conclusions:
- Rbl2p defines a second pool of beta-tubulin, regulating its availability.
- Rbl2p interaction with beta-tubulin is conformation-dependent and competitive with alpha-tubulin.
- The Rbl2p-beta-tubulin complex plays a role in cellular tubulin level and dimerization regulation.
- Rbl2p's dual effect (rescue in overexpression, deleterious in wild-type) is explained by its regulatory role.
Related Concept Videos
01:35Microtubules
There are three types of cytoskeletal structures in eukaryotic cells—microfilaments, intermediate filaments, and microtubules. With a diameter of about 25 nm, microtubules are the thickest of these fibers. Microtubules carry out a variety of functions that include cell structure and support, transport of organelles, cell motility (movement), and the separation of chromosomes during cell division.Microtubules are hollow tubes whose walls are made up of globular tubulin proteins. Each tubulin...
01:18Assembly of Cytoskeletal Filaments
Cytoskeletal filaments are polymeric forms of smaller protein subunits. However, individual cytoskeletal filaments may easily disassemble or associate with other similar filaments to form rigid structures. Microfilaments, made of actin monomers, rely on actin-binding proteins to form bundles and create networks of individual actin filaments. Microtubules rely on microtubule-associated proteins (MAPs) to form sturdy cylindrical structures. However, the proteins involved in forming complex...
01:18Microtubules
Microtubules are the thickest cytoskeletal filaments with a diameter of 25 nm. In prokaryotic organisms, microtubules are commonly found in locomotory appendages like cilia and flagella. In eukaryotic cells, microtubules form specialized extensions for moving fluid over the surface, like those found in cells lining the intestine.
Microtubules have two structurally similar globular protein subunits: α and β tubulins. In the cytosol, the α and β tubulins form a heterodimer. These αβ-heterodimers...
Microtubules have two structurally similar globular protein subunits: α and β tubulins. In the cytosol, the α and β tubulins form a heterodimer. These αβ-heterodimers...
01:23Microtubule Formation
Microtubules are dynamic structures that undergo continuous assembly and disassembly. They originate from specialized multi-protein complexes known as microtubule organizing centers or MTOCs. Within the MTOC, the point of origin of the microtubule is known as the minus end, while the end radiating outward is the plus end. Microtubules serve two primary functions — the organization of spindle complexes to separate sister chromatids during mitotic or meiotic cell division and the formation of...
01:32Assembly of Complex Microtubule Structures
Complex microtubule structures are present in resting cells and in dividing cells. In resting cells, they are responsible for maintaining the cellular architecture, tracks for intracellular transport, positioning of organelles, assembly of cilia and flagella. They mediate the bipolar spindle assembly for chromosomal segregation and positioning of the cell division plate in dividing cells. The formation of microtubule complex structures depends on the cell type, cell stage, and cell function.
02:17Microtubule Instability
Microtubules are hollow cylindrical filaments having a diameter of approximately 25 nm and a length that varies from 200 nm to 25 μm. GTP-bound tubulin subunits form αβ-heterodimers for microtubule assembly. These core building blocks interact longitudinally, polymerizing into protofilaments. The protofilaments then interact with one another through lateral bonding forces to form stable cylindrical microtubules. These cylindrical filaments are dynamic as they undergo repeated assembly and...