title: Molecular cloning and characterization of cDNA for androgen-repressible rat liver protein, SMP-2.
abstract: SMP-2 is a rat liver protein whose synthesis is influenced by both androgens and aging. The steady-state level of its mRNA is repressed by the androgen. Compared to the adult male, SMP-2 mRNA is found in higher amounts in the prepubertal and senescent male rat livers which show relative androgen insensitivity. A cDNA library in the plasmid pBR322 was constructed from the female rat liver which contains a high level of SMP-2 mRNAs. Recombinant plasmids were screened by differential colony hybridization to 32P-labeled single-stranded cDNAs from adult female and adult male hepatic poly(A)+ RNAs. From a total of 3500 recombinant clones, 11 highly female specific clones were identified. From these female specific colonies the SMP-2 cDNA-containing plasmid (pSP11) was identified by its ability to select an mRNA species whose translation product is immunochemically and electrophoretically indistinguishable from SMP-2. This insert represents a 571-base pair portion of the SMP-2 cDNA. Rescreening of the library at a high colony density using the 32P-labeled cDNA insert of pSP11 identified several positive clones with larger inserts. Hybrid-selected mRNA translation again confirmed these clones to carry SMP-2 cDNA sequences. The plasmid pSP4a containing a 1040-base pair cDNA insert of SMP-2 was characterized by DNA sequence analysis. The size of the cDNA insert of pSP4a is close to the estimated size of the SMP-2 mRNA. The cDNA sequence provides an open reading frame of 282 amino acid residues. A comparison of the translated amino acid sequence with the protein sequences of NBRF-PIR, PSQNEW, and LOSALA data bases did not establish any sequence homology with known proteins. Northern blot analysis using the 32P-labeled cDNA insert of pSP4a confirms the androgenic repression of the SMP-2 mRNA.
mesh_terms: D000595:Amino Acid Sequence; D000728:Androgens / Q000494:pharmacology*; D000818:Animals; D001483:Base Sequence; D002135:Calcium-Binding Proteins; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism*; D005260:Female; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D011919:Rats, Inbred Strains; D015238:Sulfotransferases; D014158:Transcription, Genetic
chemical_list: D000728:Androgens; D002135:Calcium-Binding Proteins; D011506:Proteins; D012333:RNA, Messenger; D004247:DNA; D015238:Sulfotransferases; C028152:alcohol sulfotransferase