Inhibition of the mobility of mouse lymphocyte surface immunoglobulins by locally bound concanavalin A.

Abstract

Fluorescence photobleaching recovery was used to study directly and quantitatively the inhibition of the lateral mobility of surface immunoglobulins (sIg) on mouse lymphocytes by localized bindingof concanavalin A (Con A) coupled to platelets. Up to a threshold occupancy of about 10% of the upper cell surface by Con A-platelets, the diffusion coefficient and mobile fraction of sIg remained as in untreated cells (5.3 x 10-10 cm2/sec and 0.65, respectively). At hi er surface occupancy, these values decreased to 8 x 10-1 cm /sec and 0.11. The magnitude of the effect was independent of the percentage occupancy above the threshold and of the distance from the bound Con A-platelets, indicating a cooperative and propagated phenomenon. Treatment with colchicine or cytochalasin B separately induced only partial reversal of the Con A-induced modulation. Treatment with both drugs together was synergistic and fully reversed the. mobility inhibition. The modulation was unaffected by NaN3 and 2-deoxyglucose, suggesting no dependence on metabolic energy. Con Aplatelets did not affect the mobility of a lipid probe. Models for the Con A-induced modulation and the relationship between the effects of Con A on sIg mobility and patch formation are discussed.

Enhanced molecular diffusibility in muscle membrane blebs: release of lateral constraints.

“…(16) who found that binding of Con A-covered platelets to 3T3 cells decreases Con A receptor mobility at cell surface points distant from the platelet. This type of global surface modulation has recently been found on lymphocytes also (17). In contrast to the slow diffusion found by Schlessinger et al (16) on normal cell surface, we find that on L6 blebs, S-Con A-labeled receptors diffuse at D = (4.0 ± 1 .0) x 10 -9 cm'/s, R = 102% ± 11% .…”

“…Interestingly, the only case in which cell surface protein has been found to diffuse nearly as fast as membrane lipid is rhodopsin in visual disks of rod outer segments, where cytoskeletal components are absent from the planes ofthe disks and other membrane proteins are scarce (14,15) . The potential subtlety of the mechanisms responsible for modulation of protein diffusibility on the cell surface is suggested by the global decreases of the diffusion coefficients ofreceptors that can be induced by strictly localized binding of concanavalin A to its receptors on a small fraction of the cell surface (16,17).…”

Distribution and lateral mobility of voltage-dependent sodium channels in neurons [published erratum appears in J Cell Biol 1989 May;108(5):preceding 2001]

“…Diffusion coefficients (DL) and mobile fractions (f) of fluorescently labeled sodium channels were measured by the spot photobleaching technique using the apparatus described previously (7,27). Measurements were carried out at 22°C.…”

“…To investigate whether anchorage modulation (27) had any role in controlling the lateral mobility of sodium channels we examined the effects of cross-linking by WGA. Administration of this ligand had no significant effect on either the diffusion coefficient or fractional recoveries.…”

Detection of Sendai virus fusion with human erythrocytes by fluorescence photobleaching recovery

“…Lateral diffusion coefficients (d) and mobile fractions (Rf) were measured by FPR [19,20] at 22"C, using an apparatus similar to the one in [21]. The monitoring laser beam (488 nm, 0.03 pW) from an argon ion laser was focused on the ghost membrane through a Zeiss Universal microscope to a spot of 0.85 gm radius, using a x 100 oilimmersion lens.…”