PMID- 6509023
OWN - NLM
STAT- MEDLINE
DCOM- 19850131
LR  - 20190613
IS  - 0006-2960 (Print)
IS  - 0006-2960 (Linking)
VI  - 23
IP  - 22
DP  - 1984 Oct 23
TI  - Deoxyguanosine nucleotide analogues: potent stimulators of microtubule nucleation 
      with reduced affinity for the exchangeable nucleotide site of tubulin.
PG  - 5314-25
AB  - Four analogues of guanosine 5'-triphosphate (GTP) (dGTP, 3'-deoxy-GTP, 
      arabinosyl-GTP, and 2',3'-dideoxy-GTP), which support more rapid and extensive 
      microtubule assembly than GTP, were hydrolyzed more rapidly than GTP in reaction 
      mixtures containing tubulin plus microtubule-associated proteins (MAPs). As with 
      GTP, hydrolysis of the four analogues was initially closely coupled to the onset 
      of polymerization and continued at a slower rate at the turbidity plateau. 
      Relative to GTP, however, these analogues (and the cognate GDP analogues), 
      particularly 3'-deoxy-GTP and 2',3'-dideoxy-GTP, bound poorly to tubulin and had 
      a reduced ability to displace bound radiolabeled GDP under nonpolymerizing 
      reaction conditions. Despite their reduced binding to the tubulin dimer, if 
      polymerization occurred, all four analogues were incorporated into microtubules 
      (as the diphosphates) in stoichiometric amounts comparable to the incorporation 
      of GTP (in the form of GDP) with displacement of the GDP initially present in the 
      exchangeable site. Microtubule nucleation was specifically enhanced in the 
      presence of the analogues. With MAPs the analogues initiated microtubule assembly 
      at temperatures 10-15 degrees C below that required by the GTP-supported 
      reaction, and the average microtubule length was significantly reduced. In 
      addition, MAP-independent polymerization occurred only with 2',3'-dideoxy-GTP 
      with tubulin at 1.0 mg/mL, with the other three analogues at 2.0 mg/mL, and with 
      GTP at 5.0 mg/mL. GTP inhibited analogue-supported polymerization at 20 degrees C 
      with MAPs and at 37 degrees C without MAPs (tubulin, 3.5 mg/mL). Both 
      3'-deoxy-GTP and 2',3'-dideoxy-GTP were poor inhibitors of GTP binding and 
      hydrolysis, but GTP potently inhibited the more vigorous hydrolysis of these 
      analogues. We conclude that alteration of the ribose moiety reduces the affinity 
      of a guanine nucleotide for the exchangeable site of tubulin but that a 
      nucleotide's affinity for this site is not the major factor in its ability to 
      support the nucleation of tubulin polymerization.
FAU - Hamel, E
AU  - Hamel E
FAU - Lustbader, J
AU  - Lustbader J
FAU - Lin, C M
AU  - Lin CM
LA  - eng
PT  - Journal Article
PL  - United States
TA  - Biochemistry
JT  - Biochemistry
JID - 0370623
RN  - 0 (Microtubule-Associated Proteins)
RN  - 0 (Polymers)
RN  - 0 (Tubulin)
RN  - 146-91-8 (Guanosine Diphosphate)
RN  - 86-01-1 (Guanosine Triphosphate)
SB  - IM
MH  - Animals
MH  - Cattle
MH  - Guanosine Diphosphate/analogs & derivatives/metabolism
MH  - Guanosine Triphosphate/*analogs & derivatives/metabolism
MH  - Hydrolysis
MH  - Microtubule-Associated Proteins/metabolism
MH  - Microtubules/*metabolism
MH  - Polymers/metabolism
MH  - Tubulin/*metabolism
EDAT- 1984/10/23 00:00
MHDA- 1984/10/23 00:01
CRDT- 1984/10/23 00:00
PHST- 1984/10/23 00:00 [pubmed]
PHST- 1984/10/23 00:01 [medline]
PHST- 1984/10/23 00:00 [entrez]
AID - 10.1021/bi00317a033 [doi]
PST - ppublish
SO  - Biochemistry. 1984 Oct 23;23(22):5314-25. doi: 10.1021/bi00317a033.