p60 Is an Adaptor for the DrosophilaPhosphoinositide 3-Kinase, Dp110*
- From the ‡Ludwig Institute for Cancer Research, 91 Riding House Street, London W1P 8BT, United Kingdom and the§MRC Graduate Programme and the ¶Department of Biochemistry and Molecular Biology, University College London, Gower Street, London WC1E 6BT, United Kingdom
Abstract
The mammalian phosphoinositide 3-kinases (PI3Ks) p110α, β, and δ form heterodimers with Src homology 2 (SH2) domain-containing adaptors such as p85α or p55PIK. The two SH2 domains of these adaptors bind to phosphotyrosine residues (pY) found within the consensus sequence pYXXM. Here we show that a heterodimer of the Drosophila PI3K, Dp110, with an adaptor, p60, can be purified from S2 cells with a pYXXM phosphopeptide affinity matrix. Using amino acid sequence from the gel-purified protein, the gene encoding p60 was cloned and mapped to the genomic region 21B8-C1, and the exon/intron structure was determined. p60 contains two SH2 domains and an inter-SH2 domain but lacks the SH3 and breakpoint cluster region homology (BH) domains found in mammalian p85α and β. Analysis of the sequence of p60 shows that the amino acids responsible for the SH2 domain binding specificity in mammalian p85α are conserved and predicts that the inter-SH2 domain has a coiled-coil structure. The Dp110·p60 complex was immunoprecipitated with p60-specific antisera and shown to possess both lipid and protein kinase activity. The complex was found in larvae, pupae, and adults, consistent with p60 functioning as the adaptor for Dp110 throughout the Drosophila life cycle.
Footnotes
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↵* The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵‖ To whom correspondence should be addressed: Ludwig Institute for Cancer Research, 91 Riding House St., London W1P 8BT, UK. Tel.: 44-171 878 4111; Fax: 44-171 878 4040; E-mail: mikew{at}ludwig.ucl.ac.uk. The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EBI Data Bank with accession number Y12498.
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↵1 The abbreviations used are: RTK, receptor tyrosine kinase; PI3K, phosphoinositide 3-kinase; pY, phosphotyrosine; SH2 and SH3, Src homology 2 and 3, respectively; BH, breakpoint cluster region homology; Class IA, the class of PI3Ks that associate with RTKs via SH2 domain-containing adaptors; PCR, polymerase chain reaction; PAGE, polyacrylamide gel electrophoresis; PLCγ, phospholipase Cγ; contig, group of overlapping clones.
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↵2 I. Gout, personal communication.
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↵3 M. J. Zvelebil, personal communication
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- Received February 27, 1997.
