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Confined diffusion of transmembrane proteins and lipids induced by the same actin meshwork lining the plasma membrane.

Fujiwara TK, Iwasawa K, Kalay Z, Tsunoyama TA, Watanabe Y, Umemura YM, Murakoshi H, Suzuki KG, Nemoto YL, Morone N, Kusumi A - Mol. Biol. Cell (2016)

Bottom Line: Electron tomography identified the actin-based membrane skeleton (MSK) located within 8.8 nm from the PM cytoplasmic surface of PtK2 cells and demonstrated that the MSK mesh size was the same as the compartment size for PM molecular diffusion.The extracellular matrix and extracellular domains of membrane proteins were not involved in hop diffusion.These results support a model of anchored TM-protein pickets lining actin-based MSK as a major mechanism for regulating diffusion.

View Article: PubMed Central - PubMed

Affiliation: Center for Meso-Bio Single-Molecule Imaging, Institute for Integrated Cell-Material Sciences, Kyoto 606-8501, Japan.

No MeSH data available.


Related in: MedlinePlus

TfR’s Deff(33 ms)100 ms (and thus hop frequency) depends on both its cytoplasmic domain size and dimerization in both PtK2 and T24 cells. (A) Molecules used for this examination. Note that endogenous TfR exists as dimers, and that since the expression levels of modified TfR molecules are much smaller than that of endogenous TfR, most of the expressed molecules are expected to form dimers with endogenous TfR. The numbers indicate the number of amino acids in the cytoplasmic domain of the endogenous human TfR (67 aa), the Halo-tag protein (297 aa), linkers (17 and 20 aa), and the cytoplasmic domain of the ACP-TM (10 aa). The expected total numbers of amino acids in the cytoplasmic domain are shown below (the endogenous TfR in PtK2 cells was assumed to have the same number of amino acids in the cytoplasmic domain as that in human TfR). (B) Distributions of the effective macroscopic diffusion coefficient Deff(33 ms)100 ms for the individual molecules in A in PtK2- and T24-cell PMs. Deff(33 ms)100 ms should be proportional to the hop frequency. For a discussion of the effect of the cross section of a diffusant on its hop characteristics, see Supplemental Notes to Figure 7B.
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Figure 7: TfR’s Deff(33 ms)100 ms (and thus hop frequency) depends on both its cytoplasmic domain size and dimerization in both PtK2 and T24 cells. (A) Molecules used for this examination. Note that endogenous TfR exists as dimers, and that since the expression levels of modified TfR molecules are much smaller than that of endogenous TfR, most of the expressed molecules are expected to form dimers with endogenous TfR. The numbers indicate the number of amino acids in the cytoplasmic domain of the endogenous human TfR (67 aa), the Halo-tag protein (297 aa), linkers (17 and 20 aa), and the cytoplasmic domain of the ACP-TM (10 aa). The expected total numbers of amino acids in the cytoplasmic domain are shown below (the endogenous TfR in PtK2 cells was assumed to have the same number of amino acids in the cytoplasmic domain as that in human TfR). (B) Distributions of the effective macroscopic diffusion coefficient Deff(33 ms)100 ms for the individual molecules in A in PtK2- and T24-cell PMs. Deff(33 ms)100 ms should be proportional to the hop frequency. For a discussion of the effect of the cross section of a diffusant on its hop characteristics, see Supplemental Notes to Figure 7B.

Mentions: For clearer presentation of the data, we focus here on results obtained in the PM of PtK2 cells (except for relevant results with Cy3-TfR and Cy3-DOPE). When comparison with results in other cell types is needed (to establish their generality), we indicate their use (see later discussions of Figures 4B, 5G, and 7B). Additional results in other cell types are shown for comparison in Supplemental Figures S1, S4, and S5.


Confined diffusion of transmembrane proteins and lipids induced by the same actin meshwork lining the plasma membrane.

Fujiwara TK, Iwasawa K, Kalay Z, Tsunoyama TA, Watanabe Y, Umemura YM, Murakoshi H, Suzuki KG, Nemoto YL, Morone N, Kusumi A - Mol. Biol. Cell (2016)

TfR’s Deff(33 ms)100 ms (and thus hop frequency) depends on both its cytoplasmic domain size and dimerization in both PtK2 and T24 cells. (A) Molecules used for this examination. Note that endogenous TfR exists as dimers, and that since the expression levels of modified TfR molecules are much smaller than that of endogenous TfR, most of the expressed molecules are expected to form dimers with endogenous TfR. The numbers indicate the number of amino acids in the cytoplasmic domain of the endogenous human TfR (67 aa), the Halo-tag protein (297 aa), linkers (17 and 20 aa), and the cytoplasmic domain of the ACP-TM (10 aa). The expected total numbers of amino acids in the cytoplasmic domain are shown below (the endogenous TfR in PtK2 cells was assumed to have the same number of amino acids in the cytoplasmic domain as that in human TfR). (B) Distributions of the effective macroscopic diffusion coefficient Deff(33 ms)100 ms for the individual molecules in A in PtK2- and T24-cell PMs. Deff(33 ms)100 ms should be proportional to the hop frequency. For a discussion of the effect of the cross section of a diffusant on its hop characteristics, see Supplemental Notes to Figure 7B.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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Figure 7: TfR’s Deff(33 ms)100 ms (and thus hop frequency) depends on both its cytoplasmic domain size and dimerization in both PtK2 and T24 cells. (A) Molecules used for this examination. Note that endogenous TfR exists as dimers, and that since the expression levels of modified TfR molecules are much smaller than that of endogenous TfR, most of the expressed molecules are expected to form dimers with endogenous TfR. The numbers indicate the number of amino acids in the cytoplasmic domain of the endogenous human TfR (67 aa), the Halo-tag protein (297 aa), linkers (17 and 20 aa), and the cytoplasmic domain of the ACP-TM (10 aa). The expected total numbers of amino acids in the cytoplasmic domain are shown below (the endogenous TfR in PtK2 cells was assumed to have the same number of amino acids in the cytoplasmic domain as that in human TfR). (B) Distributions of the effective macroscopic diffusion coefficient Deff(33 ms)100 ms for the individual molecules in A in PtK2- and T24-cell PMs. Deff(33 ms)100 ms should be proportional to the hop frequency. For a discussion of the effect of the cross section of a diffusant on its hop characteristics, see Supplemental Notes to Figure 7B.
Mentions: For clearer presentation of the data, we focus here on results obtained in the PM of PtK2 cells (except for relevant results with Cy3-TfR and Cy3-DOPE). When comparison with results in other cell types is needed (to establish their generality), we indicate their use (see later discussions of Figures 4B, 5G, and 7B). Additional results in other cell types are shown for comparison in Supplemental Figures S1, S4, and S5.

Bottom Line: Electron tomography identified the actin-based membrane skeleton (MSK) located within 8.8 nm from the PM cytoplasmic surface of PtK2 cells and demonstrated that the MSK mesh size was the same as the compartment size for PM molecular diffusion.The extracellular matrix and extracellular domains of membrane proteins were not involved in hop diffusion.These results support a model of anchored TM-protein pickets lining actin-based MSK as a major mechanism for regulating diffusion.

View Article: PubMed Central - PubMed

Affiliation: Center for Meso-Bio Single-Molecule Imaging, Institute for Integrated Cell-Material Sciences, Kyoto 606-8501, Japan.

No MeSH data available.


Related in: MedlinePlus