Nucleotide sequence of the mouse hck gene

Three-dimensional structure of the Hck SH2 domain in solution

The hematopoietic cellular kinase (Hck) is a member of the Src family of non-receptor protein-tyrosine kinases that is expressed predominantly in granulocytes, monocytes and macrophages. Recent observations suggest that Hck may be activated in HIV-infected macrophages and in chronic myelogenous leukemia cells that express Bcr-Abl. In order to increase our understanding of the structural basis for regulation of Hck activity under normal and pathological conditions, we have solved the solution structure of the uncomplexed Hck SH2 domain using NMR spectroscopy. A novel procedure that uses intraresidue HN-H alpha distances as references for converting NOE intensities into distance restraints has been described. A total of 1757 significant experimental restraints were derived from NMR spectroscopic data including 238 medium-range and 487 long-range distance restraints and 177 torsion angle restraints. These restraints were used in a simulated annealing procedure to generate 20 structures with the program DYANA. Superimposition of residues 5-104 upon the mean coordinate set yielded an average atomic rmsd values of 0.42 +/- 0.08 A for the N,C alpha,C' atoms and 0.81 +/- 0.08 A for all heavy atoms. Rmsd values for those residues in the regions of ordered secondary structure were 0.27 +/- 0.04 A for the N,C alpha,C' atoms and 0.73 +/- 0.06 A for all heavy atoms.

Sequential assignment and secondary structure determination for the Src homology 2 domain of hematopoietic cellular kinase

The hematopoietic cellular kinase (Hck) is a member of the Src family of non-receptor protein-tyrosine kinases and participates in signal transduction events regulating the growth, differentiation and function of phagocytes. The secondary structure of the SH2 domain for Hck was determined for a 13C/15N-enriched sample using multi-dimensional NMR spectroscopy. The secondary structure for the domain was determined from chemical shift indices [1H alpha, 13C alpha and 13C'], sequential NOEs [d(alphaN)(i, i+1) and d(NN)(i, i+1)], and 3J(alphaN) scalar coupling constants. The Hck SH2 domain consists of two alpha-helices and seven beta-strands. Complementary strands of beta-sheets were identified from long-range NOEs using a novel 3D, 13C/15N-edited HMQC-NOESY-(HCACO)NH experiment that correlated 1H alpha resonances between beta-strands. The secondary structure for Hck SH2 is similar to that predicted from the sequence alignment of the Src-family protein tyrosine kinases.

Cloning of BSK, a murine FRK homologue with a specific pattern of tissue distribution

A novel protein tyrosine kinase (PTK) was previously identified by us from the rat insulin-producing cell line, RINm5F, by polymerase chain reaction (PCR). By using this PCR fragment to screen a cDNA library from the mouse insulin-producing cell line beta TC-1, a cDNA clone of about 2.0 kb was obtained which encodes the entire amino acid (aa) sequence of the corresponding PTK. The deduced aa sequence reveals strong homology with the members of the SRC family of intracellular PTKs. We have designated the gene as BSK (beta-cell Src-homology tyrosine kinase). Southern blot analysis after PCR with primers specific for BSK confirmed its expression in fetal and adult islets of Langerhans, in RINm5F cells and in mouse kidney. Northern blots using poly(A)+RNA from non-beta-cell tissues showed that the BSK cDNA hybridized to three mRNA transcripts (2.9, 3.1 and 5.0 kb) present in kidney, liver and lung. Extensive homology of BSK with the recently identified human gene FRK was observed. It is concluded that Bsk is a murine Frk homologue with a specific pattern of tissue expression.

Small deletion in v-src SH3 domain of a transformation defective mutant of Rous sarcoma virus restores wild type transforming properties

RSV mutant virus PA101T was obtained while assaying the tumorigenicity of parental PA101 virus in chickens. PA101 is a transformation defective mutant of RSV which has a low src kinase activity. However, PA101 retained a temperature-sensitive ability to induce sustained proliferation of neuroretina cells. PA101T appeared as a wild-type phenotype revertant of PA101. Molecular cloning and sequencing of PA101T showed that this reversion is due to additional mutations in PA101 src gene. These mutations are a deletion eliminating three amino acids in the N-terminal region of SH3 domain and mutation of Ala 426 to Val. Analysis of the properties of chimeric src genes associating either half of PA101T with the complementary regions of PA101 or wild-type virus showed that the N-terminal moiety of PA101T src, which contains the deletion, confers wild-type transforming properties, whereas its C-terminal moiety, which contains single amino acid mutation, confers a partially temperature-sensitive phenotype. These results are consistent with other reports showing that mutations or deletions in this region of SH3 activate the transforming potential of c-src. They support the hypothesis that the N-terminal region of SH3 interacts with a cellular negative regulator of src activity.

Molecular cloning and characterization of the human double-stranded RNA-activated protein kinase induced by interferon

The double-stranded (ds) RNA-activated protein kinase from human cells is a 68 kd protein (p68 kinase) induced by interferon. On activation by dsRNA in the presence of ATP, the kinase becomes autophosphorylated and can catalyze the phosphorylation of the alpha subunit of eIF2, which leads to an inhibition of the initiation of protein synthesis. Here we report the molecular cloning and characterization of several related cDNAs from which can be deduced the full-length p68 kinase sequence. All of the cDNAs identify a 2.5 kb RNA that is strongly induced by interferon. The deduced amino acid sequence of the p68 kinase predicts a protein of 550 amino acids containing all of the conserved domains specific for members of the protein kinase family, including the catalytic domain characteristic of serine/threonine kinases. In vitro translation of a reconstructed full-length p68 kinase cDNA yields a protein of 68 kd that binds dsRNA, is recognized by a monoclonal antibody raised against the native p68 kinase, and is autophosphorylated.