| Comments |
p.1797 right column bottom paragraph:"[Investigators] then addressed the movement of mRNPs present in the vicinity of the transcription site, using a third technique. By use of a photoactivatable form of green fluorescent protein (GFP) (ref 7) fused to the MS2 protein, [they] followed the mRNPs in a “visible pulse-chase” experiment. A short pulse of activating light (405 nm) confined only to the transcription site fluorescently labeled those RNPs being actively transcribed or just released (Fig. 2, C to E). This generated an initial pool of fluorescent mRNAs that, upon release from the transcriptional machinery, diffused away from the transcription site in all directions (Fig. 2, F and G) (ref 3) [movie S11 (ref 5)]. Measurements of the area in which these mRNAs moved over time (Fig. 2G) showed a mean diffusion coefficient (D22) of 0.034 ± 0.006 µm2/sec, consistent with the range of measurements obtained by the previous two approaches (FRAP yields a D22 = 0.049 ± 0.002 µm2/sec, as discussed below and in fig. S4H). In summary, a similar range of diffusion coefficients for nuclear mRNPs was measured with three techniques." See BNID 111851, 111852 |