PMID- 7284335
OWN - NLM
STAT- MEDLINE
DCOM- 19811215
LR  - 20190613
IS  - 0006-2960 (Print)
IS  - 0006-2960 (Linking)
VI  - 20
IP  - 15
DP  - 1981 Jul 21
TI  - Characterization of rat brain crude extract microtubule assembly: correlation of 
      cold stability with the phosphorylation state of a microtubule-associated 64K 
      protein.
PG  - 4451-8
AB  - We have conducted preliminary investigations into the control of microtubule 
      assembly in rat brain crude extract supernatants. The rationale for these 
      experiments is that microtubules interact with many proteins and are undoubtedly 
      subject to physiological control mechanisms that are lost during tubulin 
      purification. A more complete understanding of the cellular regulation of 
      microtubules must include the physiology of these proteins. Assembly can be 
      monitored in rat brain crude extract high-speed supernatants by measuring the 
      increase in solution turbidity. We find that assembly is maximal in both rate and 
      extent in the absence of added nucleotide. Increasing concentrations of either 
      adenosine 5'-triphosphate (ATP) or guanosine 5'-triphosphate (GTP) inhibit both 
      initiation and elongation of microtubules. GTP appears necessary for assembly and 
      is apparently replenished from an intrinsic energy source during the time course 
      of the assembly reaction. Inhibition of GTP production prevents microtubule 
      assembly, and addition of exogenous GTP will reverse the blockage. Enzymatic 
      removal of GTP at steady state causes a rapid depolymerization to the cold-stable 
      microtubule level. Both GTP production and microtubule assembly display periodic 
      oscillatory maxima. Cold-stable microtubules, which are always present in rat 
      brain crude extract preparations, are rapidly made labile by addition of ATP. 
      Analysis of proteins in cold-stable and cold-labile microtubule fractions shows 
      changes in protein phosphorylation but not in the microtubule-associated protein 
      composition. The tentative conclusion is that the state of phosphorylation of a 
      64K protein, designated the "switch protein", determines the cold stability or 
      lability, and therefore the dimer association and dissociation rates, of crude 
      extract microtubules.
FAU - Margolis, R L
AU  - Margolis RL
FAU - Rauch, C T
AU  - Rauch CT
LA  - eng
GR  - GM 28189/GM/NIGMS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Biochemistry
JT  - Biochemistry
JID - 0370623
RN  - 0 (Microtubule-Associated Proteins)
RN  - 0 (Nerve Tissue Proteins)
RN  - 0 (Proteins)
RN  - 86-01-1 (Guanosine Triphosphate)
RN  - 8L70Q75FXE (Adenosine Triphosphate)
SB  - IM
MH  - Adenosine Triphosphate/pharmacology
MH  - Animals
MH  - Brain/*ultrastructure
MH  - Cold Temperature
MH  - Drug Stability
MH  - Guanosine Triphosphate/metabolism
MH  - Kinetics
MH  - Microtubule-Associated Proteins
MH  - Microtubules/metabolism/*ultrastructure
MH  - Nerve Tissue Proteins/*metabolism
MH  - Phosphorylation
MH  - Protein Binding
MH  - Proteins/*metabolism
MH  - Rats
MH  - Rats, Inbred Strains
EDAT- 1981/07/21 00:00
MHDA- 1981/07/21 00:01
CRDT- 1981/07/21 00:00
PHST- 1981/07/21 00:00 [pubmed]
PHST- 1981/07/21 00:01 [medline]
PHST- 1981/07/21 00:00 [entrez]
AID - 10.1021/bi00518a033 [doi]
PST - ppublish
SO  - Biochemistry. 1981 Jul 21;20(15):4451-8. doi: 10.1021/bi00518a033.