期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1973
卷号：70
期号：11
页码：3150-3154
DOI：10.1073/pnas.70.11.3150
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Cell-to-cell adhesion during aggregation of Dictyostelium discoideum cells is completely blocked by univalent antibody (Fab) directed against two classes of target sites: surface structures characteristic for aggregation-competent cells ("contact sites A") and others present also on growth-phase cells ("contact sites B"). 3 x 105 Fab molecules bound per cell are sufficient to block contact sites A completely, although the Fab fragments cover not more than 2% of the total cell surface. Up to 8-fold this value can be bound per cell when Fab fragments of another specificity are used, without affecting activity of contact sites A. Blockage of cell-to-cell adhesion therefore depends on the binding of Fab fragments to specific target sites, rather than on the total number of Fab molecules bound per cell. This conclusion is also valid for cell adhesion attributed to contact sites B. Contact sites therefore represent a special class of cell-surface sites which, in cell homogenates as well as in vivo, can be traced by Fab, and which are not identical with the bulk of cell-surface antigens present on aggregating cells.
关键词：cell contacts ; differentiation ; slime molds ; membrane factors ; cap formation by IgG
