Identification of macrophage cell-surface binding sites for cationized bovine serum albumin

1991 ◽  
Vol 181 (2) ◽  
pp. 787-796 ◽  
Author(s):  
Jan G. Dohlman ◽  
Dennis J. Pillion ◽  
Luis A. Rokeach ◽  
M.P. Ramprasad
1992 ◽  
Vol 103 (2) ◽  
pp. 565-570
Author(s):  
V. Leick

Receptor-mediated binding of leukocyte chemotactic peptide, N-formylMet-Leu-Phe (fMLP), occurs in the ciliated protozoon Tetrahymena thermophila. In vivo labelling of the cells with N-formylMet-Leu-[3H]Phe ([3H]fMLP) shows that the cells bind the ligand with high affinity (KD = 4 × 10(−9) M to 1 × 10(−8) M). Moreover, Scatchard transformations of the binding data show that there are about 5 × 10(5) binding sites per cell on the cell surface. Two fluorescent derivatives of leukocyte chemotactic peptide, N-dansylMet-Leu-Phe (dansMLP) and N-formylMet-Leu-Phe-(N-dansyl-)Lys (fMLPdanLys) compete for the N-formylMet-Leu-Phe (fMLP) binding sites on the cell surface. Moreover, both derivatives have retained significant chemoattracting potentials. Fluorescence from dansMLP, but not from fMLPdansLys and dansyl-beta-endorphin, is internalized preferentially into small vesicles. The differences may, however, reflect that the fluorescence from the dansyl group is strongly quenched by a hydrophilic microenvironment when using the two latter peptide derivatives. In contrast, the dansyl group from dansMLP must be assumed to be embedded in a hydrophobic microenvironment in the vesicular membrane or membrane protein. Rhodamine-labelled bovine serum albumin, egg albumin and cytochrome c as well as dansylated bovine serum albumin, which are poor chemoattractants, are preferentially seen to be internalized into large vesicles (food vacuoles).


1991 ◽  
Vol 266 (28) ◽  
pp. 18655-18659 ◽  
Author(s):  
P.F. Blackmore ◽  
J. Neulen ◽  
F. Lattanzio ◽  
S.J. Beebe

Development ◽  
1989 ◽  
Vol 105 (4) ◽  
pp. 795-802
Author(s):  
S.L. Goodman ◽  
R. Deutzmann ◽  
V. Nurcombe

The specific interaction of embryonal cells with the extracellular matrix (ECM) is one of the principal forces influencing embryonal development (Hay, 1984; Trinkaus, 1984). We used a muscle satellite cell line (MM14dy) to determine the relationship between locomotory response to laminin and the expression of specific cell surface binding sites for it. Time lapse videomicroscopic analysis was used to study the locomotory response and radioligand binding assays and cell attachment assays were used to follow the expression levels of binding sites for laminin and its subfragments E8 and E1–4. We report here the novel finding that the ability of MM14dy to locomote over laminin diminishes and finally vanishes as the cells differentiate. The simultaneous drop in expression of binding sites for laminin is interpreted as being of potential significance during development and repair.


1995 ◽  
Vol 269 (5) ◽  
pp. H1514-H1521 ◽  
Author(s):  
M. A. Katz ◽  
M. L. La Marche

Albumin reduces capillary hydraulic conductance (Lp) even at low concentrations. To determine if part of this barrier protective effect might be extracellular, we studied the effects of bovine serum albumin (BSA) on Lp of self-assembled basement membrane (Matrigel). Lp with tris(hydroxymethyl)aminomethane (Tris) buffer superfusate was stable at 1.77 +/- 0.22 x 10(-5) (SE) cm.s-1.cmH2O-1 over several hours. At 0.1 g/dl BSA, experimental/control (Tris) Lp fell to 83.1 +/- 6.0% (2P < 0.025), with decreases to 72.4 +/- 3.7% at 1 g/dl (2P < 0.005), 45.3 +/- 5.1% at 2.5 g/dl (2P < 0.001), and 45.0 +/- 4.8% at 4.0 g/dl (2P < 0.001). In separate experiments, BSA arginine groups were neutralized by 1,2-cyclohexanedione (CHD), and experimental/control Lp values were measured. At 2.5 g/dl, CHD-BSA depressed Lp to 54.4 +/- 4.8%, while unmodified BSA reduced Lp to 40.8 +/- 3.5% of Tris control (2P = 0.05). Finally, soluble arginine at three- and sixfold the arginine in BSA was added to BSA superfusate. For threefold, Lp rose to 120 +/- 8% of BSA level and for sixfold to 129 +/- 9% (2P < 0.05). We conclude that some part of the albumin protective effect is very likely due to consequences on extracellular matrix and that at least 18-22% of this effect is related to arginine groups on albumin when computed from Lp, and up to 34% when viscosity is taken into account. Membrane-saturable arginine-binding sites can be unbound with arginine, thus nullifying part of the barrier protective effect of BSA.


Viruses ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 427 ◽  
Author(s):  
Sergey Buth ◽  
Mikhail Shneider ◽  
Dean Scholl ◽  
Petr Leiman

The R-type pyocins are high-molecular weight bacteriocins produced by some strains of Pseudomonas aeruginosa to specifically kill other strains of the same species. Structurally, the R-type pyocins are similar to “simple” contractile tails, such as those of phage P2 and Mu. The pyocin recognizes and binds to its target with the help of fibers that emanate from the baseplate structure at one end of the particle. Subsequently, the pyocin contracts its sheath and drives the rigid tube through the host cell envelope. This causes depolarization of the cytoplasmic membrane and cell death. The host cell surface-binding fiber is ~340 Å-long and is attached to the baseplate with its N-terminal domain. Here, we report the crystal structures of C-terminal fragments of the R1 and R2 pyocin fibers that comprise the distal, receptor-binding part of the protein. Both proteins are ~240 Å-long homotrimers in which slender rod-like domains are interspersed with more globular domains—two tandem knob domains in the N-terminal part of the fragment and a lectin-like domain at its C-terminus. The putative substrate binding sites are separated by about 100 Å, suggesting that binding of the fiber to the cell surface causes the fiber to adopt a certain orientation relative to the baseplate and this then triggers sheath contraction.


Sign in / Sign up

Export Citation Format

Share Document