Hulmes D J, Bruns R R, Gross J
Proc Natl Acad Sci U S A. 1983 Jan;80(2):388-92. doi: 10.1073/pnas.80.2.388.
Procollagen and partially processed procollagen from cultures of primary chicken embryo tendon cells appeared as segment-long-spacing (SLS)-like aggregates when drops of medium were negatively stained and examined by electron microscopy. Similar aggregates were obtained after negative staining of medium partially purified by gel filtration and also after staining thin sections of fixed, dehydrated, and embedded pellets formed by prolonged ultracentrifugation of whole culture medium. In contrast to results from electron microscopy, analysis by velocity density gradient sedimentation or sedimentation equilibrium indicated the exclusive presence of procollagen or partially processed procollagen monomers in solution. These contradictory data can be reconciled if procollagen exists in monomeric form when greatly diluted (as in culture medium), and in specific aggregated form (SLS) at high concentration. We believe that cells in vivo secrete procollagen in high, local concentration packaged in the SLS form. We propose that such zero-D arrayed packages are the precursors of native collagen fibrils.
当对原代鸡胚肌腱细胞培养物中的前胶原和部分加工的前胶原进行负染色并通过电子显微镜检查时，培养基液滴呈现出类似片段长间距（SLS）的聚集体。对经凝胶过滤部分纯化的培养基进行负染色后，以及对通过对全培养基进行长时间超速离心形成的固定、脱水和包埋的沉淀块的薄片进行染色后，也获得了类似的聚集体。与电子显微镜结果相反，速度密度梯度沉降或沉降平衡分析表明溶液中仅存在前胶原或部分加工的前胶原单体。如果前胶原在极大稀释时（如在培养基中）以单体形式存在，而在高浓度时以特定的聚集形式（SLS）存在，那么这些相互矛盾的数据就可以得到解释。我们认为，体内细胞以高局部浓度分泌包装成SLS形式的前胶原。我们提出，这种零维排列的包装是天然胶原纤维的前体。
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