Abstract
Protein phosphatases play a critical role in the regulation of the eukaryotic cell cycle and signal transduction. A putative protein serine/threonine phosphatase gene has been isolated from the human malaria parasite Plasmodium falciparum. The gene has an unusual intron that contains four repeats of 32 nucleotides and displays a high degree of size polymorphism among different strains of P. falciparum. The open reading frame reconstituted by removal of the intron encodes a protein of 466 amino acids with a predicted molecular mass of approximately 53.7 kDa. The encoded protein, termed protein phosphatase β (PP-β), is composed of two distinct domains. The C-terminal domain comprises 315 amino acids and exhibits a striking similarity to the catalytic subunits of the type-2A protein phosphatases. Database searches revealed that the catalytic domain has the highest similarity to Schiwsaccharomyces pombe Ppal (58% identity and 73% similarity). However, it contains a hydrophilic insert consisting of five amino acids. The N-terminal domain comprises 151 amino acid residues and exhibits several striking features, including high levels of charged amino acids and asparagine, and multiple consensus phosphorylation sites for a number of protein kinases. An overall structural comparison of PP-β with other members of the protein phosphatase 2A group revealed that PP-β is more closely related to Saccharomyces cerevisiae PPH22. Southern blots of genomic DNA digests and chromosomal separations showed that PP-β is a single-copy gene and is located on chromosome 9. A 2800-nucleotide transcript of this gene is expressed specifically in the sexual erythrocytic stage (gametocytes). The results indicate that PP-β may be involved in sexual stage development.
DOI
10.1111/j.1432-1033.1997.t01-2-00098.x
Publication Date
1997-10-01
Publication Title
European Journal of Biochemistry
Volume
249
Issue
1
Publisher
Wiley
ISSN
1432-1033
Embargo Period
2024-11-19
First Page
98
Last Page
106
Recommended Citation
Li, J., & Baker, D. (1997) 'Protein Phosphatase β, a Putative Type‐2A Protein Phosphatase from the Human Malaria Parasite Plasmodium Falciparum', European Journal of Biochemistry, 249(1), pp. 98-106. Wiley: Available at: https://doi.org/10.1111/j.1432-1033.1997.t01-2-00098.x
