Microtubules from chicken erythrocytes and brain tissue contain beta tubulin variants that can be biochemically distinguished by differences in electrophoretic properties and in primary structure as revealed by peptide mapping. These differences are reflected by differences in polypeptide composition, assembly properties, solubility and stability of microtubules. It is possible that the beta tubulin variants are different gene products. We propose to examine this possibility and determine how differences in tubulin assembly and function are related to differences in tubulin structure. The unique properties of erythrocyte tubulin and the finding that erythroblasts may not contain the beta tubulin variant will also allow us to use antibodies to examine differentiating blood cells to examine gene switching, protein sorting, and differential utilization of tubulin variants in development. Three areas of investigation are proposed. (1) Peptide mapping of beta tubulin subunits and amino acid sequencing of specific peptides will be done to explain the shift in isoelectric points (0.3 pH unit) and establish if the tubulin variants are different gene products. Particular attention will be given to the acidic carboxyl-terminal peptide since variation in the beta tubulin sequence is predicted to occur in this position. (2) Surface domains involved in interactions among tubulin subunits and MAPs will be identified by 'zero-length crosslinking"""""""" with a water-soluble carbodiimide together with partial digestion with proteases and SDS gel electrophoretic analysis (Sutoh, 1982). (3) Rabbit antibodies to """"""""total tubulin"""""""" and to """"""""erythrocyte beta tubulin"""""""" will be used to examine the time of appearance (tubulin gene switching) and sites of incorporation (protein sorting and compartmentalization) of tubulin variants during chicken red cell differentiation. By immuno-electron microscopy we will determine if protein sorting occurs at the molecular level, preventing the formation of copolymers of the tubulin variants.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM033171-02
Application #
3282556
Study Section
Cellular Biology and Physiology Subcommittee 1 (CBY)
Project Start
1984-01-01
Project End
1986-12-31
Budget Start
1985-01-01
Budget End
1985-12-31
Support Year
2
Fiscal Year
1985
Total Cost
Indirect Cost
Name
Johns Hopkins University
Department
Type
Schools of Medicine
DUNS #
045911138
City
Baltimore
State
MD
Country
United States
Zip Code
21218
Kaiser, D A; Vinson, V K; Murphy, D B et al. (1999) Profilin is predominantly associated with monomeric actin in Acanthamoeba. J Cell Sci 112 ( Pt 21):3779-90
Parent, C A; Blacklock, B J; Froehlich, W M et al. (1998) G protein signaling events are activated at the leading edge of chemotactic cells. Cell 95:81-91
Schmitz, F; Wallis, K T; Rho, M et al. (1994) Intracellular distribution of kinesin in chromaffin cells. Eur J Cell Biol 63:77-83
Wallis, K T; Azhar, S; Rho, M B et al. (1993) The mechanism of equilibrium binding of microtubule-associated protein 2 to microtubules. Binding is a multi-phasic process and exhibits positive cooperativity. J Biol Chem 268:15158-67
Baker, H N; Rothwell, S W; Grasser, W A et al. (1990) Copolymerization of two distinct tubulin isotypes during microtubule assembly in vitro. J Cell Biol 110:97-104
Azhar, S; Murphy, D B (1990) Structural plugs at microtubule ends may regulate polymer dynamics in vitro. Cell Motil Cytoskeleton 15:156-61
Kuznetsov, S A; Vaisberg, Y A; Rothwell, S W et al. (1989) Isolation of a 45-kDa fragment from the kinesin heavy chain with enhanced ATPase and microtubule-binding activities. J Biol Chem 264:589-95
Murphy, D B; Gray, R O; Grasser, W A et al. (1988) Direct demonstration of actin filament annealing in vitro. J Cell Biol 106:1947-54
Rothwell, S W; Grasser, W A; Baker, H N et al. (1987) The relative contributions of polymer annealing and subunit exchange to microtubule dynamics in vitro. J Cell Biol 105:863-74
Murphy, D B; Wallis, K T; Machlin, P S et al. (1987) The sequence and expression of the divergent beta-tubulin in chicken erythrocytes. J Biol Chem 262:14305-12

Showing the most recent 10 out of 15 publications