Embryonic and hematopoietic stem cells express a novel SH2-containing inositol 5'-phosphatase isoform that partners with the Grb2 adapter protein.
SH2-containing inositol 5'-phosphatase (SHIP) modulates the activation of immune cells after recruitment to the membrane by Shc and the cytoplasmic tails of receptors. A novel SHIP isoform of approximately 104 kd expressed in primitive stem cell populations (s-SHIP) is described. It was found that s-SHIP is expressed in totipotent embryonic stem cells to the exclusion of the 145-kd SHIP isoform expressed in differentiated hematopoietic cells. s-SHIP is also expressed in primitive hematopoietic stem cells, but not in lineage-committed hematopoietic cells. In embryonic stem cells, s-SHIP partners with the adapter protein Grb2 without tyrosine phosphorylation and is present constitutively at the cell membrane. It is postulated that s-SHIP modulates the activation threshold of primitive stem cell populations.
Tu
Z
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Immunology Program, the H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612, USA.
Ninos
J M
JM
Ma
Z
Z
Wang
J W
JW
Lemos
M P
MP
Desponts
C
C
Ghansah
T
T
Howson
J M
JM
Kerr
W G
WG
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D004622:Embryo, Mammalian / Q000166:cytology / Q000201:enzymology*; D005091:Exons; D005260:Female; D006412:Hematopoietic Stem Cells / Q000201:enzymology* / Q000378:metabolism; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid; D015398:Signal Transduction; D018909:src Homology Domains
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D007527:Isoenzymes; C498726:Mona protein, mouse; D012333:RNA, Messenger; D010744:Phosphoric Monoester Hydrolases; C021822:myo-inositol-1 (or 4)-monophosphatase