Expression and characterisation of a Plasmodium falciparum protein containing domains homologous to sarcalumenin and a tyrosine kinase substrate, eps15.
We have identified in Plasmodium falciparum a novel gene encoding a putative bi-functional protein, termed PfPast-1, from genomic and cDNA libraries. Analysis indicated that the sequence encodes a 62 kDa protein of 529 amino acid residues with two distinctive domains: a sarcalumenin-like domain of approximately 320 amino acids at the amino half of the molecule, which shares homology to a major sarcoplasmic reticulum lumenal protein, sarcalumenin, and an eps15 homology domain of about 90 amino acids located at the carboxyl terminus. The eps15 homology domain, first identified in a tyrosine kinase substrate, eps15, and found in increasing numbers of mammalian proteins, has recently been suggested as a protein-protein interaction domain involved in intracellular sorting. Genomic sequences encoding similar proteins containing both the sarcalumenin-like and eps15 homology domains have been identified in humans and Drosophila. RNA blot analysis revealed the presence of a single messenger RNA transcript approximately 3.7 kb in size, which is expressed in all the developmental stages examined with the highest level in extracellular gametes followed by erythrocytic asexual stages, and the lowest in the gametocytes. In the attempt to define its biological function, we have expressed a full-length recombinant PfPast-1 protein in Escherichia coli. Specific immune serum directed against the recombinant protein recognised a approximately 55 kDa protein in the parasite lysate. Further characterisation of PfPast-1 may help in elucidation of its functions in P. falciparum.
Center for Biologics Evaluation and Research, Food and Drug Administration, Rockville, MD 20852-1448, USA. mcdaniel@cber.fda.gov
J P
JP
McDaniel
C
C
Syin
D T
DT
Lin
M B
MB
Joshi
S
S
Li
N D
ND
Goldman
D000595:Amino Acid Sequence; D000818:Animals; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D017125:Genes, Protozoan / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D010963:Plasmodium falciparum / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment
D002135:Calcium-Binding Proteins; D008565:Membrane Proteins; C120518:Past-1 protein, Plasmodium falciparum; D010750:Phosphoproteins; D015800:Protozoan Proteins; C070323:sarcalumenin; D011505:Protein-Tyrosine Kinases