title: The CDK5 activator, p39, binds specifically to myosin essential light chain.
abstract: Cyclin-dependent kinase 5 (Cdk5) has been shown to regulate adhesion and migration of lens and corneal epithelial cells. To explore protein-protein interactions that may mediate these functions, we performed yeast two-hybrid screening on an embryonic rat lens library using Cdk5 and its regulators, p35 and p39 as baits. This screen identified an interaction between p39 and non-muscle myosin essential light chain (MLC(17)). GST pull-down experiments demonstrated that p39 binds directly to MLC(17) through a strong binding site in the N-terminal 109 amino acids of p39. Immunoprecipitation of proteins from Cos1 cells co-transfected with GFP-MLC(17) and HA-p39 confirmed that these proteins interact intracellularly. Immunofluorescence microscopy of co-transfected lens epithelial cells showed that GFP-MLC(17) and HA-p39 co-localize along cytoskeletal fibrils. Moreover, endogenous rat lens p39 co-immunoprecipitated with MLC(17) and myosin heavy chain II (MHC II), demonstrating that the interaction is physiological and serves to link p39 to the cytoskeleton.
authors.affiliation: Laboratory of Molecular and Developmental Biology, National Eye Institute, National Institutes of Health, Building 7, Room 102, MSC 0704, Bethesda, MD 20892, USA.
authors.forename: Dolena R
authors.initials: DR
authors.lastname: Ledee
authors.forename: Brajendra K
authors.initials: BK
authors.lastname: Tripathi
authors.forename: Peggy S
authors.initials: PS
authors.lastname: Zelenka
mesh_terms: D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002522:Chlorocebus aethiops; D051360:Cyclin-Dependent Kinase 5 / Q000378:metabolism; D007908:Lens, Crystalline / Q000166:cytology / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000378:metabolism; D018994:Myosin Light Chains / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D013347:Subcellular Fractions / Q000737:chemistry; D020798:Two-Hybrid System Techniques
chemical_list: C108298:Cdk5 activator p39; D018994:Myosin Light Chains; D009419:Nerve Tissue Proteins; D051360:Cyclin-Dependent Kinase 5; D018995:Myosin Heavy Chains