Animal Cell Technology: Developments towards the 21st Century, pp501-507, 1995.

Immunoglobulin Production Stimulating Activities of Nucleic Acid-binding Proteins.

Takuya Sugahara, Sanataka Shirahata, Takeshi Sasaki, and Hiroki Murakami


Immunoglobulin production stimulating factor-II (IPSF-II) has been purified and identified as glyceraldehyde-3-phosphate dehydrogenase (GPD) on the basis of amino acid sequence and enzymatic activity. IPSF-II enhances immunoglobulin production of human-human and mouse-mouse hybridomas in serum-free condition. However, there was no correlation between the IPSF activity and the enzymatic activity. This indicates that enhancement of immunoglobulin production with GPD is not linked with its enzymatic function. It is known that GPD has not only enzymatic activity in glycolytic pathway but binding activity with nucleic acids, such as single-strand DNA and RNA. Therefore, in this paper we investigated IPSF activities of some nucleic acid-binding proteins and poly basic-amino acids. Though histone H1, H2A and H2B categorized into lysine-rich histones enhanced immunoglobulin productivity of human-human hybridoma HB4C5 cells, histone H3 and H4 categorized into arginine-rich showed hardly any enhancement activities. Arginine-rich protein, protamine did not show IPSF activities as same as arginine-rich histones.