Sugahara T, Shirahata S, Akiyoshi K, Isobe T, Okuyama T, Murakami H
Department of Food Science and Technology, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.
Cytotechnology. 1991 Jun;6(2):115-20. doi: 10.1007/BF00373028.
Amino acid sequence of the 36 KD protein which is the active subunit of immunoglobulin production stimulating factor-II alpha (IPSF-II alpha) derived from Burkitt's lymphoma Namalwa cells was analyzed for the 20 amino acids from N-terminus. The N-terminal amino acid sequence of this protein coincided very closely with glyceraldehyde-3-phosphate dehydrogenase (GPD; EC 1.2.1.12) derived from various origins. Especially, it was completely homologous with that of human liver GPD. Several GPD's derived from human erythrocyte, rabbit muscle and Bacillus stearothermophilus also stimulated IgM production of hybridomas, as well as IPSF-II alpha. Conversely, IPSF-II alpha had GPD enzymic activity as strong as rabbit muscle and B. stearothermophilus, and stronger than human erythrocyte GPD. These results suggested that 36 KD subunit of IPSF-II alpha was a GPD, or GPD like protein. The level of mRNA for IgM was not enhanced by IPSF-II alpha in hybridoma cells, though the IgM productivity of the cell was remarkably stimulated by the protein, indicating that IPSF-II alpha does not stimulate immunoglobulin production by enhancement of transcription.
对源自伯基特淋巴瘤Namalwa细胞的免疫球蛋白产生刺激因子-IIα（IPSF-IIα）的活性亚基36KD蛋白的氨基酸序列，从N端开始分析了20个氨基酸。该蛋白的N端氨基酸序列与源自各种来源的甘油醛-3-磷酸脱氢酶（GPD；EC 1.2.1.12）非常接近。特别是，它与人肝GPD的序列完全同源。源自人红细胞、兔肌肉和嗜热栖热放线菌的几种GPD也能刺激杂交瘤产生IgM，IPSF-IIα也有此作用。相反，IPSF-IIα具有与兔肌肉和嗜热栖热放线菌一样强的GPD酶活性，且比人红细胞GPD的活性更强。这些结果表明，IPSF-IIα的36KD亚基是一种GPD或类GPD蛋白。尽管IPSF-IIα能显著刺激杂交瘤细胞产生IgM，但它并未增强杂交瘤细胞中IgM的mRNA水平，这表明IPSF-IIα不是通过增强转录来刺激免疫球蛋白产生的。
