Table - link
||Mammalian tissue culture cell
||Hirschberg K et al., Kinetic analysis of secretory protein traffic and characterization of golgi to plasma membrane transport intermediates in living cells. J Cell Biol. 1998 Dec 14 143(6):1485-503. p.1490 table IPubMed ID9852146
||Abstract: "Quantitative time-lapse imaging data of single cells expressing the transmembrane protein, vesicular stomatitis virus ts045 G protein fused to green fluorescent protein (VSVG-GFP), were used for kinetic modeling of protein traffic through the various compartments of the secretory pathway. A series of first order rate laws was sufficient to accurately describe VSVG-GFP transport, and provided compartment residence times and rate constants for transport into and out of the Golgi complex and delivery to the plasma membrane."
||P.1490 left column 4th to 6th paragraphs: "Table I summarizes the mean rate constants (± standard error) from the model solutions obtained from analysis of the 32 cells (in five separate experiments). The mean rate constant for VSVG–GFP export out of the ER (KER) was 2.84 ± 0.20% per minute, whereas export out of the Golgi complex (KG) was 3.03 ± 0.26% per minute. Degradation (KPM) of VSVG–GFP occurred at a rate of 0.25 ± 0.03% per minute from plasma membrane-derived membranes.
To illustrate the sensitivity of the fit to changes in rate constants, curves of simulated data are shown in Fig. 2 D where [investigators] increased either KER (red curve) or KG (blue curve) by a factor of 1.8 and allowed the remaining parameters to readjust. The discrepancies in these fits to the experimental data are substantial. For comparison, the black lines show the optimized fit. The standard error in Table I and Fig. 1 D, therefore, reflects cell-to-cell variability, rather than the error in any one fit.
The average time spent by a single VSVG–GFP molecule in the ER, Golgi, or plasma membrane (i.e., mean residence time) as it moved through the secretory pathway was obtained by inverting the optimized rate constants cell by cell and then averaging (Table I). [They] found that a VSVG–GFP molecule spends on average about the same time in the Golgi complex as in the ER compartment: mean residence time was ∼40 min for each. In contrast, mean residence time in the plasma membrane and its associated membranes before degradation was ∼700 min." See notes beneath table