Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving antigen-antibody binding – specific binding protein...
Reexamination Certificate
1998-05-27
2001-08-14
Housel, James C. (Department: 1641)
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving antigen-antibody binding, specific binding protein...
C435S006120, C435S007100, C435S007200, C435S007800, C435S015000, C435S021000, C435S069100, C435S069200, C435S194000, C435S252300, C435S348000, C514S263370, C530S350000
Reexamination Certificate
active
06274327
ABSTRACT:
This invention relates to new polypeptides which exhibit kinase activity. More specifically, the invention is concerned with polypeptides which show phosphoinositide (hereinafter “PI”) 3-kinase activity, particularly molecules involved in pathways responsible for cellular growth and differentiation.
Major advances have taken place in our knowledge of the structure and function of the signal transducing molecules and second messenger systems coupled to cell surface receptors. Thus, a subset of polypeptide growth factor receptors belong to the family of protein-tyrosine kinases (hereinafter “PTK” and activation of these receptors following ligand binding involves autophosphorylation of the receptor as well as phosphorylation of a number of intracellular substrate proteins (reviewed in Ullrich, A et al., 1990). The importance of receptor autophosphorylation had been unclear until recently, when evidence from several laboratories has suggested that this event may mediate the formation of complexes between receptor proteins and putative growth regulatory proteins such as phospholipase PI3-kinase (Coughlin, S R et al, 1989). GTPase-activating protein (GAP) (Kaplan et al, 1990), the serine/theonine kinase Raf (Morrison et al, 1989), and members of the src-family of protein-tyrosine kinases (Kypta, R M et al., 1990) (reviewed in Cantley, L C et al., 1991).
The association of PI kinase activity with activated receptors is of particular interest since increased turnover of PI and its phosphorylated derivatives has been implicated in the action of hormones, growth factors and transformation of cells by DNA and RNA viruses (reviewed in Whitman, M et al., 1988; Cantley et al., 1991). Several species of PI kinase are known to exist, but up to now none of these enzymes have been characterised by cloning and expression and the demonstration of PI kinase activity. Fibroblasts contain at least two PI kinase activities which are distinguishable on the basis of their detergent sensitivity and kinetic properties (Whitman, M et al., 1987). These two activities were classified as Type I (inhibited by non-ionic detergents) and Type II (stimulated by non-ionic detergents and inhibited by adenosine). A third distinct species (Type III) has been identified in bovine brain but remains poorly characterised (Enderman, G et al., 1987). One species of PI kinase activity in particular has become of major interest in the search for second messenger systems linked to protein-tyrosine kinases because this activity was shown to co-immunoprecipitate with activated platelet-derived growth factor (PDGF) receptors (Kaplan, D R et al., 1987; Coughlin, S R et al., 1989) and with the polyoma middle T antigen/pp60
c-src
(mT:pp60
c-src
) complex (Whitman, M et al., 1985). This activity has been shown to be due to a Type I PI kinase which produces novel inositol lipids phosphorylated at the D-
3
position of the inositol ring (Whitman, M et al., 1988). More recently this enzyme has also been shown to associate with the CSF-
1
receptor (Varticovski, L et al., 1989) kit (Lev et al, 1991), the epidermal growth factor (EGF) receptor (Bjorge et al, 1990), the PDGF a-receptor (Yu et al, 1991), the insulin receptor (Ruderman et al, 1990), the hepatocyte growth factor receptor, Met (Graziani et al, 1991), and with activated non-receptor protein-tyrosine kinases (Fukui & Hanafusa, 1989; Chan et al, 1990; Varticovski et al, 1991).
PI3 kinase activity has been closely linked to the presence of 81/85 kD proteins in these immunoprecipitates which can be phosphorylated on tyrosine residues by the associated protein-tyrosine kinase both in vitro and in vivo (Kaplan, D R et al., 1987; Courtneidge, S A et al., 1987; Cohen et al, 1990). Recently a 650 fold purification of PI
3-
kinase from bovine brain was described which, among other proteins present in the purest preparation, contained an 85 kD protein which was shown to be an in vitro substrate for the PDGF and EGF receptors (Morgan, S J et al., 1990). Using sequence information from tryptic peptides derived from this protein, two homologous bovine p85 proteins, denoted p85&agr; and p85&bgr; (Otsu, M et al., 1991) have recently been cloned. Two other groups have independently cloned murine and human p85&agr; homologues using different strategies (Escobedo, J A et al., 1991b; Skolnik, E Y et al., 1991). Both of these p85 proteins can be demonstrated to bind directly to phosphorylated PDGF receptor in vitro (Otsu, M et al., 1991; Escobedo, J A et al., 1991b). These proteins may function as the receptor binding subunits of the PI3-kinase since neither of them can be shown to encode intrinsic PI3-kinase activity when expressed in a variety of cell systems (Otsu, M et al., 1991; Escobedo, J A et al., 1991b). However, immunoprecipitation of
125
I-labelled bovine brain PI3-kinase with antibodies raised against p85 proteins precipitates an 85 kD protein together with a second protein of molecular weight 110 kD (Otsu, M et al., 1991).
PI3-kinase is one of a growing number of potential signalling proteins which associate with protein-tyrosine kinases activated either by ligand stimulation or as a consequence of cell transformation. A common feature of all these proteins (apart from Raf), is that they contain one or more SH2 domains (
s
rc
h
omology) (Koch, C A et al., 1991). Both p85&agr; and p85&bgr; proteins contain two SH2 domains. Experiments from a number of laboratories have suggested that these domains may function by binding to peptide sequences usually phosphorylated on tyrosine residues, and thus mediate the complex formation which follows activation of protein-tyrosine kinases (Anderson et al, 1990; Meyer & Hanafusa, 1990; Moran et al, 1990; Matsuda et al, 1991; Meyer et al, 1991; reviewed in Koch, C A et al., 1991). In support of this, several studies suggest that tyrosine phosphorylation of the PDGF receptor or polyoma mT is essential for its association with proteins such as the PI3-kinase (Kazlauskas, A et al., 1989; Talmage, D A et al., 1989) GAP (Kaplan et al, 1990; Kazlauskas, A et al., 1990) and PLC&ggr; (Anderson et al, 1990; Margolis et al, 1990). The precise tyrosine residue required for binding of the PI3-kinase activity (and an 85 kD phosphoprotein) to the human PDGF receptor has been mapped to tyrosine 751 which lies within the kinase insert region of the protein-tyrosine kinase domain (Kazlauskas & Cooper, 1989, 1990; Kazlauskas et al, 1991). The binding sites for other proteins to this receptor (eg., PLC&ggr;, GAP and src-family kinases) have yet to be mapped, but these proteins may associate via other phosphorylated tyrosine residues.
This invention has been facilitated by the finding that certain synthesized peptides from the human PDGF &bgr;-receptor, namely peptides derived from the sequence around tyrosine
751
of the PDGF receptor, can be used to bind and isolate bovine brain PI3-kinase, making it possible to purify further partially purified bovine brain PI3-kinase (as described by Morgan et al, 1990) to apparent homogeneity and to obtain reasonably pure p110 protein. As will be described hereinafter, the PI3-kinase requires a phosphopeptide column containing a YXXM motif for its isolation by such a technique, the tyrosine being phosphorylated. Only if a column of this type is used are both the 85 kD and 110 kD proteins secured whereas 85 kD subunit binds to all phosphopeptide affinity columns tested and only fails to bind to non-phosphorylated peptides. Moreover, the relatively small size of the phosphopeptides used for such columns gives good specificity and a high density of affinity groups per unit volume of column.
This purification has allowed amino acid sequence information to be provided, and cDNA cloning to be performed. Such cloning has revealed some interesting facts. Thus, p110 is a 1068 amino acid protein having an unexpectedly high (compared to SDS-PAGE FIGS.) calculated molecular weight of about 124 kD (124247). The protein is related to Vps34p, a Saccharomyces cerevisiae protein involved in the sorting of proteins to the vacuole. Surprisingly
Dhand Ritu
Fry Michael J.
Gout Ivan
Hiles Ian D.
Otsu Masayuki
Hines Ja-Na A.
Housel James C.
Ludwig Institute for Cancer Research
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