The protein-tyrosine kinase p56(lck) is a member of the src-family of oncogene encoded proteins. The proximity of these family members to the plasma membrane coupled with their proven ability to transform cells has suggested a role for these proteins in transducing extracellular activation signals. This suggestion has been strengthened by the recent findings that several of these traditionally non-receptor tyrosine kinases are indeed receptor associated. This proposal focuses on p56(lck), a lymphocyte- specific tyrosine kinase found associated with the transmembrane receptors CD4 and CD8. This proposal addresses the hypothesis that p56(lck) is a component of a signaling complex whose localization to the plasma membrane is necessary for its proper functioning. The testing of this hypothesis will be approached by 1) identifying and characterizing members of the complex which may serve as substrates for p56(lck) (p56(lck)-associated proteins); 2) characterizing potential complex-members that modify p56(lck) (protein kinases for which p56(lck) serves as a substrate); and 3) defining structural modifications of p56(lck) which direct complex formation. This proposal offers evidence for two potential substrates for p56(lck), for two potential kinases which phosphorylate p56(lck) and for the fatty acylation of p56(lck) by palmitoylation. Strategies are presented for understanding how each of these factors contributes to the functioning of the p56(lck) signaling complex. The methodologies used in this proposal include: 1) protein purification, 2) lymphocyte activation studies using normal mouse lymphocytes and transformed lymphocyte cell lines, 3) biosynthetic labeling and peptide mapping, 4) immunoprecipitations and immune complex kinase assays, 5) immunoblot analysis, 6) myristoylation inhibition studies, 7) cellular distribution and localization studies, and 8) screening of protein expression libraries and DNA cloning. An appreciation of the normal functioning of p56(lck) is critical to understanding how its inappropriate regulation can cause cell transformation.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
Project #
Application #
Study Section
Cellular Biology and Physiology Subcommittee 1 (CBY)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Purdue University
Schools of Pharmacy
West Lafayette
United States
Zip Code
Jennings, Benjamin C; Nadolski, Marissa J; Ling, Yiping et al. (2009) 2-Bromopalmitate and 2-(2-hydroxy-5-nitro-benzylidene)-benzo[b]thiophen-3-one inhibit DHHC-mediated palmitoylation in vitro. J Lipid Res 50:233-42
Li, Manqing; Ong, Su Sien; Rajwa, Bartek et al. (2008) The SH3 domain of Lck modulates T-cell receptor-dependent activation of extracellular signal-regulated kinase through activation of Raf-1. Mol Cell Biol 28:630-41
Krzysiak, Amanda J; Rawat, Diwan S; Scott, Sarah A et al. (2007) Combinatorial modulation of protein prenylation. ACS Chem Biol 2:385-9
Geahlen, Robert L; Handley, Misty D; Harrison, Marietta L (2004) Molecular interdiction of Src-family kinase signaling in hematopoietic cells. Oncogene 23:8024-32
Hawash, Ibrahim Y; Kesavan, Kamala P; Magee, Anthony I et al. (2002) The Lck SH3 domain negatively regulates localization to lipid rafts through an interaction with c-Cbl. J Biol Chem 277:5683-91
Kesavan, Kamala P; Isaacson, Christina C; Ashendel, Curtis L et al. (2002) Characterization of the in vivo sites of serine phosphorylation on Lck identifying serine 59 as a site of mitotic phosphorylation. J Biol Chem 277:14666-73
Hawash, Ibrahim Y; Hu, X Eric; Adal, Adiam et al. (2002) The oxygen-substituted palmitic acid analogue, 13-oxypalmitic acid, inhibits Lck localization to lipid rafts and T cell signaling. Biochim Biophys Acta 1589:140-50
Pathan, N I; Geahlen, R L; Harrison, M L (1996) The protein-tyrosine kinase Lck associates with and is phosphorylated by Cdc2. J Biol Chem 271:27517-23
Pathan, N I; Ashendel, C L; Geahlen, R L et al. (1996) Activation of T cell Raf-1 at mitosis requires the protein-tyrosine kinase Lck. J Biol Chem 271:30315-7
Ford, C E; Furlong, M T; Geahlen, R L et al. (1994) Signaling-induced association of a tyrosine-phosphorylated 36-kDa protein with p50csk. J Biol Chem 269:30378-85

Showing the most recent 10 out of 12 publications