title: Differential effects of colchicine and cytochalasins on the shedding of murine B cell membrane IgM and IgD.
abstract: Lactoperoxidase (EC 1.11.1.7) catalyzed cell surface radioiodination was employed to monitor  the fate of murine B cell membrane (mem) IgM and IgD on radiolabeled cells in short-term culture. Both mem-IgM and mem-IgD were shed from the cell surface with biphasic kinetics. The rapid phase of mem-IgD shedding was somewhat slower (half-time = 12 hr) than that of mem-IgM shedding (half-time = 7-8 hr). The effect of temperature, colchicine, and cytochalasin on the shedding of the two membrane immunoglobulin isotypes was determined. The shedding of mem-IgD was more energy dependent than that of mem-IgM and was sensitive to colchicine but not cytochalasin. Conversely, the shedding of mem-IgM was sensitive to cytochalasin but not colchicine. The results suggest that the mechanisms of shedding of mem-IgM and mem-IgD are qualitatively distinct and may be regulated by microfilaments or microtubules, respectively.
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D003078:Colchicine / Q000494:pharmacology*; D003572:Cytochalasins / Q000494:pharmacology*; D003599:Cytoskeleton / Q000502:physiology; D007072:Immunoglobulin D / Q000378:metabolism*; D007075:Immunoglobulin M / Q000378:metabolism*; D007700:Kinetics; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008870:Microtubules / Q000502:physiology; D013696:Temperature
chemical_list: D003572:Cytochalasins; D007072:Immunoglobulin D; D007075:Immunoglobulin M; D008565:Membrane Proteins; D003078:Colchicine