Cooper G W, Prockop D J
J Cell Biol. 1968 Sep;38(3):523-37. doi: 10.1083/jcb.38.3.523.
The synthesis of collagen can be interrupted, after the assembly of proline-rich and lysine-rich polypeptide chains called protocollagen, by incubating connective tissues anaerobically. Under these conditions the proline and lysine residues in protocollagen are not hydroxylated to hydroxyproline and hydroxylysine, and protocollagen molecules accumulate intracellularly. Chemical data and radioautographs at the level of the light and electron microscopes indicated that in tissues labeled with proline-3,4-(3)H under nitrogen, there appeared to be an accumulation of radioactivity over the ground cytoplasm. When the inhibition of protocollagen hydroxylase was reversed by exposing the tissue to oxygen, the accumulated protocollagen-(3)H was converted to collagen-(3)H and there was a rapid transfer of label from the ground cytoplasm to the extracellular matrix. There was no significant change in distribution of label over either the Golgi vacuoles or the cisternae of the endoplasmic reticulum. The failure to find a significant change in distribution of label over the Golgi vacuoles or the cisternae does not completely exclude the possibility that these two compartments are involved in the extrusion, but the data are consistent with the simpler notion that the completed collagen molecules pass directly from the ground cytoplasm to the extracellular matrix.
在富含脯氨酸和赖氨酸的多肽链（称为原胶原）组装完成后，通过对结缔组织进行厌氧培养，胶原的合成可被中断。在这些条件下，原胶原中的脯氨酸和赖氨酸残基不会被羟基化为羟脯氨酸和羟赖氨酸，原胶原分子在细胞内积累。光镜和电镜水平的化学数据及放射自显影片表明，在用氮标记的3,4-(3)H-脯氨酸处理的组织中，在基础细胞质上似乎有放射性积累。当通过将组织暴露于氧气来逆转原胶原羟化酶的抑制作用时，积累的原胶原-(3)H被转化为胶原-(3)H，并且标记物迅速从基础细胞质转移到细胞外基质。在高尔基体空泡或内质网池上标记物的分布没有显著变化。在高尔基体空泡或池上未发现标记物分布有显著变化，并不能完全排除这两个区室参与挤出过程的可能性，但这些数据与更简单的观点一致，即完整的胶原分子直接从基础细胞质传递到细胞外基质。
