title: Beta thymosins as actin binding peptides.
abstract: The beta thymosins are a highly conserved family of strongly polar 5 kDa polypeptides that are widely distributed among vertebrate classes; most are now known to bind to monomeric actin and inhibit its polymerization. One beta thymosin, beta four, (T beta 4) is the predominant form in mammalian cells, present at up to 0.5 mM. Many species are known to produce at least two beta thymosin isoforms, in some cases in the same cell. Their expression can be separately regulated. When present outside the cell, the N-terminal tetrapeptide of beta four appears to affect cell cycle regulation; beta thymosins or smaller fragments derived from them may have additional regulatory functions. We suggest that many developmental changes in beta thymosin levels within cells and tissues may be related to changes in G-actin pool size.
authors.affiliation: Department of Cell and Developmental Biology, School of Medicine, University of Pennsylvania, Philadelphia 19104-6058.
authors.forename: D
authors.initials: D
authors.lastname: Safer
authors.forename: V T
authors.initials: VT
authors.lastname: Nachmias
mesh_terms: D000199:Actins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D006801:Humans; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D013947:Thymosin / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D008840:Microfilament Proteins; D012333:RNA, Messenger; D013947:Thymosin