title: The role of a conserved membrane proximal cysteine in altering αPS2CβPS integrin diffusion.
abstract: Cysteine residues (Cys) in the membrane proximal region are common post-translational modification (PTM) sites in transmembrane proteins. Herein, the effects of a highly conserved membrane proximal α-subunit Cys1368on the diffusion properties of αPS2CβPS integrins are reported. Sequence alignment shows that this cysteine is palmitoylated in human α3 and α6 integrin subunits. Replacing Cys1368in wild-type integrins with valine (Val1368) putatively blocks a PTM site and alters integrins' ligand binding and diffusion characteristics. Both fluorescence recovery after photobleaching (FRAP) and single particle tracking (SPT) diffusion measurements show Val1368integrins are more mobile compared to wild-type integrins. Approximately 33% and 8% more Val1368integrins are mobile as measured by FRAP and SPT, respectively. The mobile Val1368integrins also exhibit less time-dependent diffusion, as measured by FRAP. Tandem mass spectrometry data suggest that Cys1368contains a redox or palmitoylation PTM in αPS2CβPS integrins. This membrane proximal Cys may play an important role in the diffusion of other alpha subunits that contain this conserved residue.
authors.affiliation: Department of Chemistry, Iowa State University, 1605 Gilman Hall, Ames, IA 50011, USA.
authors.forename: Aleem
authors.initials: A
authors.lastname: Syed
authors.forename: Neha
authors.initials: N
authors.lastname: Arora
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Bunch
authors.forename: Emily A
authors.initials: EA
authors.lastname: Smith
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D001671:Biochemistry / Q000379:methods; D003545:Cysteine / Q000737:chemistry / Q000378:metabolism*; D004058:Diffusion; D004330:Drosophila / Q000235:genetics; D029721:Drosophila Proteins / Q000737:chemistry; D036681:Fluorescence Recovery After Photobleaching / Q000379:methods; D039001:Integrin alpha Chains / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics; D046188:Protein Modification, Translational; D014633:Valine / Q000737:chemistry / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D029721:Drosophila Proteins; D039001:Integrin alpha Chains; D008164:Luminescent Proteins; C082188:if protein, Drosophila; C054562:yellow fluorescent protein, Bacteria; D014633:Valine; D003545:Cysteine