Project: Research project

Project Details


A serine protein kinase, S6 kinase, is specific for the ribosomal
protein S6 in 40S subunits. S6 kinase is activated by a variety
of mitogenic agents. In vitro evidence suggests that
phosphorylated S6 subunits are preferentially utilized in forming
the initiation complex in protein synthesis. Also, S6 kinase
activity is stimulated during maturation of Xenopus oocytes induced
by progesterone or insulin. The mechanism of activation of S6 kinase in vivo is poorly
understood. As the purification of S6 kinase has been difficult,
a number of important questions concerning the activation of the
protein, the regulation of mRNA expression, and the organization
of the S6 kinase gene remain. Recently the cDNA for Xenopus S6
kinase was isolated. Using that cDNA as a probe, the human S6
kinase cDNA will be obtained. These cDNAs will be expressed in a Baculovirus expression vector
system. Native and mutagenized proteins will be produced and
questions concerning the activation and regulation of the enzyme
will be addressed. Polyclonal and monoclonal antibodies against
the proteins will be produced to aid in the characterization. The activation of S6 kinase is very rapid, suggesting the
involvement of post-translational modifications. The level of
induction and the half-life of mRNA will be determined in order to
define parameters of transcriptional regulation of the gene. The
transcription and potential processing of the mRNA will be studied
with the idea of sorting out whether this kinase clone is part of
a larger S6 kinase gene family. The genomic organization of the human kinase will be explored. The
5' and 3' regions of the gene will be examined to gain
understanding of transcriptional regulation. The chromosomal
localization of the gene will be determined by somatic cell hybrid
analysis and in situ hybridization. Should the gene be localized
to an area associated with chromosomal breakpoints or growth
factors, more extensive mapping of the region will be undertaken
to determine if gene amplification or rearrangement is present. AS S6 kinase is stimulated through many separate pathways it seems
likely this enzyme is involved in disordered cell growth or
differentiation. Its high degree of activity in lymphoid tissue
suggest a role in lymphoid development. The high level of
conservation across many species suggests a forefront role for this
kinase in the control of cell growth. Abnormalities in this enzyme
may be key to the understanding of such disease as childhood
lymphoblastic leukemia.
Effective start/end date7/1/896/30/94


  • National Institutes of Health
  • National Institutes of Health: $91,033.00
  • National Institutes of Health: $89,923.00
  • National Institutes of Health
  • National Institutes of Health


  • Medicine(all)


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