The binding and processing of mannose-bovine serum albumin derivatives by rabbit alveolar macrophages. Effect of the sugar density.

摘要: Mammalian alveolar macrophages are known to bind, internalize, and degrade glycoconjugates containing terminal D-mannosyl residues such as bovine serum albumin modified with 2-imino-2-methoxyethyl 1-thio-alpha-D-mannopyranoside (Mann-AI-BSA) (Lee, Y. C., Stowell, C.P., Krantz, M. J. (1976) Biochemistry 15, 3956-3963). In this report, the binding (2 degrees C) initial uptake (37 of Mann-AI-BSA (n = 5, 13, 24, 43) by rabbit were examined. Man43-AI-BSA had about 400 times higher affinity (Kd 2.0 nM) for macrophage than Man5-AI-BSA ligand 820 at 2 C. Kinetic analysis 125I-Man43-AI-BSA C yielded an association rate constant 1.2 X 10(6) M-1 min-1 a dissociation 5.9 10(-3) (t1/2 117 min). The 37 was orders magnitude greater When endocytotic process analyzed Michaelis-Menten-type kinetics, K 20 that (328 18 nM, respectively). maximal velocities were, however, very similar all four Man-AI-BSA derivatives (62,600-83,000 molecules/cell/min). constants internalization hydrolysis 125I-Man13-AI-BSA determined using steady state approach. 125I-Man43-AI-BSA, 1.23 (+/- 0.20) min-1, obtained 125I-Man13-AI-BSA, 1.80 0.67) min-1. two ligands also close, 7.4 0.2) 10(-2) 9.2 0.5) respectively.