Expression pattern and subcellular localization of five splice isoforms of human PXK.
Phox homology (PX) domains specifically bind to phosphoinositides, and this interaction is crucial for their cellular function. A full-length cDNA of human PX domain containing serine/threonine kinase gene (PXK) that we termed PXK_v1 had previously been cloned. PXK_v1 consists of a S_TKc domain (serine/threonine kinases, catalytic domain), but lacks several residues that are indispensable for intrinsic catalytic activity. Evidence obtained in the present study demonstrated the existence of four other splice isoforms of human PXK in fetal brain, designated as PXK_v2, PXK_v3, PXK_v4 and PXK_v5. The results of RT-PCR indicated that human PXK_v1, PXK_v2 and PXK_v4 transcripts were widely expressed in human adult tissue, except heart tissue. In contrast, PXK_v3 transcripts were only expressed in peripheral blood leukocytes at a low level and PXK_v5 transcripts were not detectable in any of the tissue analyzed. Subcellular localization analysis of EGFP-PXK fusion proteins in COS7 cells indicated that EGFP-PXK_v3 had a different subcellular localization compared to other EGFP-PXK fusion proteins. Mutation analysis of EGFP-PXK_v1 showed that PXK_v1-Tyr56 and Arg92 are essential for subcellular localization of the protein in the cytoplasm.
Zou
Xianqiong
X
State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai 200433, PR China.
Qiu
Guanzhou
G
Chen
Chunjing
C
Wu
Maoqing
M
Hu
Yuehua
Y
Zheng
Huarui
H
Li
Xin
X
Gu
Shaohua
S
Ji
Chaoneng
C
Mao
Yumin
Y
D017398:Alternative Splicing / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000378:metabolism; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D005260:Female; D020869:Gene Expression Profiling; D015723:Gene Library; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008297:Male; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009419:Nerve Tissue Proteins; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014162:Transfection
D018076:DNA, Complementary; D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes; D009419:Nerve Tissue Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; C508327:PXK protein, human; D017346:Protein Serine-Threonine Kinases