title: At least three linear regions but not the zinc-finger domain of U1C protein are exposed at the surface of the protein in solution and on the human spliceosomal U1 snRNP particle.
abstract: No structural information on U1C protein either in its free state or bound to the spliceosomal U1 small nuclear ribonucleoprotein (snRNP) particle is currently available. Using rabbit antibodies raised against a complete set of 15 U1C overlapping synthetic peptides (16-30 residues long) in different immunochemical tests, linear regions exposed at the surface of free and U1 snRNP-bound U1C were identified. Epitopes within at least three regions spanning residues 31-62, 85-103 and 116-159 were recognized on free and plastic-immobilized recombinant human U1C expressed in Escherichia coli, on in vitro translated U1C protein and on U1C bound to the U1 snRNP particle present in HeLa S100 extract. Using a zinc affinity labeling method, we further showed that the N-terminal U1C peptide containing a zinc-finger motif (peptide 5-34) effectively binds65Zn2+. The N-terminal region of U1C, which is functional in U1 snRNP assembly, is apparently not located at the surface of the U1 snRNP particle.
authors.affiliation: Institut de Biologie Moléculaire et Cellulaire, UPR 9021 CNRS, 15 rue Descartes, 67000 Strasbourg, France.
authors.forename: H
authors.initials: H
authors.lastname: Dumortier
authors.forename: J
authors.initials: J
authors.lastname: Klein Gunnewiek
authors.forename: J P
authors.initials: JP
authors.lastname: Roussel
authors.forename: Y
authors.initials: Y
authors.lastname: van Aarssen
authors.forename: J P
authors.initials: JP
authors.lastname: Briand
authors.forename: W J
authors.initials: WJ
authors.lastname: van Venrooij
authors.forename: S
authors.initials: S
authors.lastname: Muller
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011817:Rabbits; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000737:chemistry / Q000378:metabolism*; D017411:Ribonucleoproteins, Small Nuclear / Q000737:chemistry / Q000378:metabolism*; D012996:Solutions; D017381:Spliceosomes / Q000737:chemistry / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism; D016335:Zinc Fingers
chemical_list: D010446:Peptide Fragments; D017412:Ribonucleoprotein, U1 Small Nuclear; D017411:Ribonucleoproteins, Small Nuclear; C491260:SNRPC protein, human; D012996:Solutions; D015032:Zinc