PMID- 3994984
OWN - NLM
STAT- MEDLINE
DCOM- 19850702
LR  - 20190613
IS  - 0006-2960 (Print)
IS  - 0006-2960 (Linking)
VI  - 24
IP  - 3
DP  - 1985 Jan 29
TI  - Release of exchangeably bound guanine nucleotides from tubulin in a 
      magnesium-free buffer.
PG  - 768-75
AB  - The number of moles of guanine nucleotides (denoted GXP), either guanosine 
      5'-triphosphate (GTP) or guanosine 5'-diphosphate (GDP), bound to a mole of 
      phosphocellulose-purified tubulin after gel filtration into a variety of 
      nucleotide-free buffers has been measured (H. B. Croom, J. J. Correia, and R. C. 
      Williams, Jr., unpublished results). All buffers we have studied that promote 
      reduction of the number of bound nucleotides to fewer than two per tubulin dimer 
      also eventually cause irreversible loss of activity of the protein. However, in 
      0.1 M 1,4-piperazinediethanesulfonic acid (pH 6.9) and 2 mM dithioerythritol 
      (with no Mg2+), tubulin rapidly releases approximately 0.4 mol of bound 
      nucleotides during two successive gel filtrations requiring less than 0.5 h and 
      regains the ability to polymerize when magnesium and GTP are immediately added to 
      the buffer. No change in conformation detectable by circular dichroism or 
      sedimentation velocity accompanies this reversible process. (Upon prolonged 
      incubation in the buffer, however, tubulin undergoes irreversible changes 
      according to apparent first-order kinetics with a half-life of approximately 8 h. 
      These changes include the irreversible release of nucleotide, a loss of the 
      ability to polymerize, and a decrease in molar ellipticity between 210 and 240 
      nm.) The nucleotide which is reversibly released in this buffer comes from that 
      population which exchanges readily with [3H]GTP in vitro.(ABSTRACT TRUNCATED AT 
      250 WORDS)
FAU - Croom, H B
AU  - Croom HB
FAU - Correia, J J
AU  - Correia JJ
FAU - Baty, L T
AU  - Baty LT
FAU - Williams, R C Jr
AU  - Williams RC Jr
LA  - eng
GR  - GM07319/GM/NIGMS NIH HHS/United States
GR  - GM25638/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 (Buffers)
RN  - 0 (Guanine Nucleotides)
RN  - 0 (Microtubule-Associated Proteins)
RN  - 0 (Tubulin)
RN  - 146-91-8 (Guanosine Diphosphate)
RN  - 86-01-1 (Guanosine Triphosphate)
RN  - I38ZP9992A (Magnesium)
SB  - IM
MH  - Animals
MH  - Brain/metabolism
MH  - Buffers
MH  - Cattle
MH  - Guanine Nucleotides/*metabolism
MH  - Guanosine Diphosphate/*metabolism
MH  - Guanosine Triphosphate/*metabolism
MH  - Kinetics
MH  - Magnesium/*pharmacology
MH  - Microtubule-Associated Proteins/metabolism
MH  - Protein Binding
MH  - Protein Conformation
MH  - Tubulin/*metabolism
EDAT- 1985/01/29 00:00
MHDA- 2001/03/28 10:01
CRDT- 1985/01/29 00:00
PHST- 1985/01/29 00:00 [pubmed]
PHST- 2001/03/28 10:01 [medline]
PHST- 1985/01/29 00:00 [entrez]
AID - 10.1021/bi00324a035 [doi]
PST - ppublish
SO  - Biochemistry. 1985 Jan 29;24(3):768-75. doi: 10.1021/bi00324a035.