Matrin CYP, an SR-rich cyclophilin that associates with the nuclear matrix and splicing factors.
We report the identification and cloning of a nuclear matrix protein termed matrin cyclophilin or matrin CYP. The derived sequence of matrin cyp encodes a protein of 752 amino acids with a predicted mass of 88 kDa. A 172-residue stretch at the amino terminus shows high identity with the ubiquitous family of cyclophilins. Clustered throughout the carboxyl half of the protein are a series of serine-arginine (SR) repeats that are a characteristic feature of many RNA splicing factors. Antibodies raised against matrin CYP recognize a 106-kDa antigen that is detected in isolated nuclei and quantitatively subfractionates in the nuclear matrix. Laser scanning confocal microscopy localizes most of the anti-matrin CYP-specific antigen within the nucleus in a pattern of large bright speckles that co-localize with splicing factors and diffuse nucleoplasmic staining. A strikingly similar pattern of staining is observed in cells extracted for in situ nuclear matrices. A fusion protein containing the cyclophilin domain of matrin CYP exhibits cyclosporin A (CsA)-sensitive, peptidylprolyl cis-trans-isomerase activity that is characteristic of native cyclophilins. Although total rat liver nuclei contains predominantly CsA-resistant PPIase activity, the corresponding activity in the nuclear matrix is largely CsA-sensitive.
Mortillaro
M J
MJ
Department of Biological Sciences, State University of New York, Buffalo, New York 14260, USA.
Berezney
R
R
D000595:Amino Acid Sequence; D000818:Animals; D034961:Antigens, Nuclear; D001120:Arginine; D001483:Base Sequence; D003001:Cloning, Molecular; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics*; D019696:Peptidylprolyl Isomerase / Q000235:genetics* / Q000302:isolation & purification; D012326:RNA Splicing; D051381:Rats; D012694:Serine
D034961:Antigens, Nuclear; D009687:Nuclear Proteins; D012694:Serine; D001120:Arginine; D019696:Peptidylprolyl Isomerase