Human malaria parasites display a receptor for activated C kinase ortholog.
Receptors for activated C kinases (RACKs) are scaffold proteins that anchor diverse signaling proteins and are involved in modulating cell cycle. We report the cloning and cellular localization of a RACK ortholog (PfRACK) in the human malaria parasite Plasmodium falciparum. The full-length transcript obtained by 3(') and 5(') RACE has 1.4 kbp with a predicted ORF of 972 bp, coding for a protein with 323 residues of 35.8 kDa molecular weight and pI 6.38. PfRACK has 59% and 60% identity at the amino acid level to Chlamydomonas reinhardtii and Danio rerio RACKs, respectively, presenting seven WD40 motifs and retaining the conserved domains in repeats III (DVFSVSF) and VI (STINSLCF) that are important for PKC binding. Semi-quantitative RT-PCR revealed that PfRACK is constitutively expressed in the intraerythrocytic stages of P. falciparum. Using confocal microscopy, PfRACK was immunolocalized in all parasite stages, being conspicuously spread throughout the schizont. The high similarity of PfRACK to those previously described in other organisms, as well as its constitutive expression in Plasmodium asexual stages, suggests that it might play a key role in the regulatory processes of malaria parasite life cycle.
Madeira
Luciana
L
Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, 05508-900, São Paulo, SP, Brazil.
DeMarco
Ricardo
R
Gazarini
Marcos L
ML
Verjovski-Almeida
Sergio
S
Garcia
Célia R S
CR
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D015153:Blotting, Western; D002453:Cell Cycle; D003001:Cloning, Molecular; D004912:Erythrocytes / Q000469:parasitology; D006801:Humans; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000494:pharmacology; D016366:Open Reading Frames; D010963:Plasmodium falciparum; D011485:Protein Binding; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction
D009841:Oligonucleotides; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface