Dynamic and stable populations of microtubules in cells.
Using a new immunocytochemical technique, we have visualized the spatial arrangement of those microtubules in cells that are stable to biotin-tubulin incorporation after microinjection. Cells fixed at various periods of time after injection were exposed to antibody to biotinylated tubulin and several layers of secondary antibodies; these layers prevented reaction of biotin-containing microtubules with antitubulin antibodies. The microtubules that had not incorporated biotin-tubulin could then be stained with anti-tubulin and a fluorescent secondary antibody. In BSC1 cells, most microtubules in the cell exchange with a half-time of 10 min. A separate population of microtubules can be detected, using the above techniques, that are stable to exchange for 1 h or more; these have a characteristic pericentrosomal spatial arrangement as compared to the majority of dynamic microtubules. Unlike the dynamic microtubules, most of the stable microtubules are nongrowing. The average BSC-1 cell contains approximately 700 microtubules: approximately 500 growing at 4 micron min-1, 100 shrinking at approximately 20 micron min-1, and approximately 100 that are relatively more stable to exchange. The potential significance of these stable microtubules is discussed.
D000818:Animals; D000906:Antibodies; D001562:Benzimidazoles / Q000494:pharmacology; D002460:Cell Line; D002522:Chlorocebus aethiops; D005455:Fluorescent Antibody Technique; D007668:Kidney; D007700:Kinetics; D008870:Microtubules / Q000648:ultrastructure*; D015739:Nocodazole; D014404:Tubulin / Q000378:metabolism*
D000906:Antibodies; D001562:Benzimidazoles; D014404:Tubulin; D015739:Nocodazole