Mosevitsky M I, Novitskaya V A, Iogannsen M G, Zabezhinsky M A
Leningrad Nuclear Physics Institute, Academy of Sciences of the USSR, Gatchina.
Eur J Biochem. 1989 Nov 6;185(2):303-10. doi: 10.1111/j.1432-1033.1989.tb15116.x.
The levels and distribution between nucleus and cytoplasm of HMG1 and HMG2 proteins have been investigated in different tissues of mammals. In lymphoid tissues and testis high amounts of these proteins are present in both nuclei and cytoplasm, while in the hepatic tissues and brain they accumulate in cytoplasm, mainly in the cytosol. In particular, very low amounts, if any, of HMG1 and 2 are present in the nuclei active for DNA replication (rat regenerating liver and primary hepatoma) or transcription (adult liver and brain). Therefore, it appears that HMG1 and 2 are not necessary for these processes. On the other hand, nuclear (chromosomal) HMG1 and 2 are characteristic for the tissues containing undifferentiated cells: lymphoid tissues, testis, neonatal liver. These proteins are bound to the chromatin regions solubilized early by sonication or DNase action. Comparison of the data obtained for different tissues shows an inverse correlation between the amounts of chromosomal HMG1 and 2, on the one hand, and of histone H1(0), on the other hand. These results suggest that chromosomal HMG1 and 2 take part in the processes that occur during cell differentiation, while histone H1(0) is induced to preserve differentiated cells from dedifferentiation.
已对哺乳动物不同组织中HMG1和HMG2蛋白的水平及其在细胞核与细胞质之间的分布进行了研究。在淋巴组织和睾丸中，这些蛋白在细胞核和细胞质中均大量存在，而在肝组织和脑中，它们则在细胞质中积累，主要是在胞质溶胶中。特别是，在对DNA复制（大鼠再生肝和原发性肝癌）或转录（成年肝脏和脑）有活性的细胞核中，HMG1和2的含量极低，甚至可能不存在。因此，看来HMG1和2对于这些过程并非必需。另一方面，核（染色体）HMG1和2是含有未分化细胞的组织的特征：淋巴组织、睾丸、新生肝脏。这些蛋白与通过超声处理或DNase作用早期溶解的染色质区域结合。对不同组织获得的数据进行比较表明，一方面染色体HMG1和2的量与另一方面组蛋白H1(0)的量之间呈负相关。这些结果表明，染色体HMG1和2参与细胞分化过程中发生的过程，而组蛋白H1(0)被诱导以保护分化细胞不发生去分化。
