title: Poly(L-proline)-binding proteins from chick embryos are a profilin and a profilactin.
abstract: Two poly(L-proline)-binding proteins (PBP-1 and PBP-2) were purified from chick embryos by using a poly(L-proline)-agarose column. PBP-1 was composed of two different polypeptides (molecular masses of 42 kDa and 15 kDa). The molar ratio of the two proteins in the complex was 1:1. The other poly(L-proline)-binding protein, PBP-2, was the 15-kDa protein itself. The 42-kDa protein was confirmed to be an actin from the amino acid composition, by immunochemical evidence and by its ability to self-polymerize. In addition, the 42 + 15-kDa protein complex (PBP-1) inhibited DNase I, just as a monomeric actin did. The amino acid composition of the 15-kDa protein was similar to that of mammalian profilin and it inhibited the salt-induced polymerization of rabbit skeletal muscle actin. Therefore, we conclude that the two poly(L-proline)-binding proteins from the chick embryo are a profilactin and a profilin in chick embryo. The ability of profilactin to bind poly(L-proline) must be due to profilin itself, because the profilin has a greater affinity for poly(L-proline) than does profilactin. Additionally, both the monomeric and filamentous actin from rabbit skeletal muscle have no affinity for poly(L-proline).
mesh_terms: D000199:Actins / Q000378:metabolism; D026921:Amino Acid Transport Systems, Neutral; D000818:Animals; D002352:Carrier Proteins / Q000302:isolation & purification*; D002642:Chick Embryo; D002846:Chromatography, Affinity; D003285:Contractile Proteins; D004591:Electrophoresis, Polyacrylamide Gel; D005779:Immunodiffusion; D008840:Microfilament Proteins; D008970:Molecular Weight; D010455:Peptides / Q000378:metabolism*; D051304:Profilins; D011487:Protein Conformation; D011506:Proteins / Q000302:isolation & purification*
chemical_list: D000199:Actins; D026921:Amino Acid Transport Systems, Neutral; D002352:Carrier Proteins; D003285:Contractile Proteins; D008840:Microfilament Proteins; D010455:Peptides; D051304:Profilins; D011506:Proteins; C024782:profilactin; C041832:proline transport protein; C011083:polyproline