Scapinin, a putative protein phosphatase-1 regulatory subunit associated with the nuclear nonchromatin structure.
It is thought that the nuclear nonchromatin structures, such as the nuclear matrix and lamina, play regulatory roles in gene expression. In this study, we identified an insoluble protein that was associated with the chromatin-depleted nuclear structure of proliferating human leukemia HL-60 cells. Preparation of the chromatin-depleted nuclear structure, referred to as the nuclear matrix-intermediate filament scaffold (Fey, E., Krochmalnic, G., and Penman, S. (1986) J. Cell. Biol. 102, 1654-1665), involved cell extraction using a series of buffers containing Triton X-100, DNase I, and 2 M NaCl. A yeast two-hybrid assay revealed that this protein bound to the catalytic subunit of protein phosphatase-1 (PP1). Furthermore, it inhibited PP1 activity in vitro. We therefore named it scapinin (scaffold-associated PP1 inhibiting protein). cDNA cloning revealed that scapinin had two splicing variants of 448 amino acids (scapinin-S) and 518 amino acids (scapinin-L). Scapinin was down-regulated by differentiation in HL-60 cells. These results suggest that scapinin is a putative regulatory subunit of PP1 and is involved in transformed or immature phenotypes of HL-60 cells. We also describe the presence of scapinin family proteins from worm to human.
Sagara
Junji
J
Department of Molecular Oncology, Institute on Aging and Adaptation, Shinshu University Graduate School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan. sagara@sch.md.shinshu-u.ac.jp
Higuchi
Tsukasa
T
Hattori
Yukiko
Y
Moriya
Mie
M
Sarvotham
Haritha
H
Shima
Hiroshi
H
Shirato
Haruki
H
Kikuchi
Kunimi
K
Taniguchi
Shunichiro
S
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D015152:Blotting, Northern; D002021:Buffers; D017173:Caenorhabditis elegans; D002454:Cell Differentiation; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D003902:Detergents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004331:Drosophila melanogaster; D020224:Expressed Sequence Tags; D049452:Green Fluorescent Proteins; D018922:HL-60 Cells; D006657:Histones; D006801:Humans; D008164:Luminescent Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry* / Q000502:physiology*; D010749:Phosphoprotein Phosphatases / Q000737:chemistry* / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D054645:Protein Phosphatase 1; D017434:Protein Structure, Tertiary; D012259:Ribonuclease, Pancreatic / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D020798:Two-Hybrid System Techniques
D000911:Antibodies, Monoclonal; D002021:Buffers; D002843:Chromatin; D018076:DNA, Complementary; D003902:Detergents; D006657:Histones; D008164:Luminescent Proteins; D009687:Nuclear Proteins; C479826:PHACTR3 protein, human; D049452:Green Fluorescent Proteins; D012259:Ribonuclease, Pancreatic; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1