Protein 4.2 (P4.2) comprises -5% of the protein mass of human erythrocyte (RBC) membranes. Anemia occurs in patients with RBCs deficient in P4.2, suggesting a role for this protein in maintaining RBC stability and integrity. We now report the molecular cloning and characterization of human RBC P4.2 cDNAs. By immunoscreening a human reticulocyte cDNA library and by using the polymerase chain reaction, two cDNA sequences of 2.4 and 2.5 kilobases (kb) were obtained. These cDNAs differ only by a 90-base-pair insert in the longer isoform located three codons downstream from the putative initiation site. The 2.4-and 2.5-kb cDNAs predict proteins of -77 and =80 kDa, respectively, and the authenticity was confimed by sequence identity with 46 amino acids of three cyanogen bromide-cleaved peptides of P4. Subcloning and Sequence Analysis. cDNA inserts from positive phage clones were subcloned into pBS(+) plasmids (Stratagene). Unidirectional deletion clones were generated by using BAL-31 exonuclease (13), and cDNA fragments were sequenced with T3 and T7 primers by the dideoxynucleotide chain-termination method (14). Sequence analysis and GenBank data base searches were performed by IBI Pustell sequence analysis software (International Biotechnologies). 5'-End Extension of cDNA. Three oligonucleotides were prepared in a technique based on the polymerase chain reaction (PCR) to synthesize the missing 5' sequence of the partial cDNA clone: pl was composed of nucleotides (nt) 7-23 of clone 7 (c.7); p2 was complementary to nt 36-52 of c.7 plus an EcoRI restriction site at its 5' end; p3 was composed of the EcoRI polylinker and the poly(dC) originally used for the first-strand cDNA synthesis when the library was constructed. The sequences of pl, p2, and p3 were, respectively, 5'-dTGAGGATGCTGTGTTCC-3', 5'-dTCGAAlJCGTACTC-CATGCGCTGAG-3', and 5'-dGCGGLAAlTCCCCCCCCCC-CCCC-3', with the EcoRI sites underlined. p2 and p3 were used as PCR primers, and the reticulocyte cDNA library (5 ,u with 106 phages per pl) was used as a template. The reaction product was electrophoresed and stained with ethidium bromide. The major band was excised and subcloned into pGEM 3zf plasmids (Promega). From >500 transformants, 24 colonies were randomly chosen to make minipreparations of plasmid DNA, of which 80%o were positive when hybridized with 32P-labeled pl. tTo whom reprint requests should be addressed. IThe sequences reported in this paper have been deposited in the GenBank data base (accession nos. M30646 and M30647).
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Gender differences in performance on the obstetrics and gynecology clerkship have been reported, with female students outperforming male students. Male students report that their gender negatively affects their experience during the clerkship. Additionally, there are fewer male students applying for obstetric/gynecology residency. This "To The Point" article by the Association of Professors of Gynecology and Obstetrics Undergraduate Medical Education Committee will describe the gender differences that have been found, examine factors that could be contributing to these issues, and propose measures to correct these disparities.
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