Mono-ADP-ribosylation, a post-translational modification in which the ADP-ribose moiety of NAD is transferred to an acceptor protein, is catalyzed by a family of amino acid-specific ADP-ribosyltransferases. ADP-ribosyltransferase 5 (ART5), a murine transferase originally isolated from Yac-1 lymphoma cells, differed in properties from previously identified eukaryotic transferases in that it exhibited significant NAD glycohydrolase (NADase) activity. To investigate the mechanism of regulation of transferase and NADase activities, ART5 was synthesized as a FLAG fusion protein in Escherichia coli. Agmatine was used as the ADP-ribose acceptor to quantify transferase activity. ART5 was found to be primarily an NADase at 10 M NAD, whereas at higher NAD concentrations (1 mM), after some delay, transferase activity increased, whereas NADase activity fell. This change in catalytic activity was correlated with auto-ADP-ribosylation and occurred in a time-and NAD concentration-dependent manner. Based on the change in mobility of auto-ADP-ribosylated ART5 by SDS-polyacrylamide gel electrophoresis, the modification appeared to be stoichiometric and resulted in the addition of at least two ADP-ribose moieties. Auto-ADP-ribosylated ART5 isolated after incubation with NAD was primarily a transferase. These findings suggest that auto-ADP-ribosylation of ART5 was stoichiometric, resulted in at least two modifications and converted ART5 from an NADase to a transferase, and could be one mechanism for regulating enzyme activity.Mono-ADP-ribosylation is a post-translational modification of proteins catalyzed by enzymes that transfer the ADP-ribose moiety of NAD to specific amino acids in protein acceptors (1, 2). The best characterized mono-ADP-ribosylation reactions are those catalyzed by bacterial toxin ADP-ribosyltransferases such as cholera (3), diphtheria (4), and pertussis (5) toxins, which alter critical metabolic and regulatory pathways. For example, cholera toxin ADP-ribosylates an arginine in the ␣-subunit of the stimulatory heterotrimeric guanine nucleotidebinding protein (G protein), resulting in the activation of adenylyl cyclase and an increase in intracellular cyclic AMP (3).Mono-ADP-ribosyltransferase activity specific for arginine has been detected in numerous animal tissues (2, 6 -14). Transferases have been cloned from rabbit (7) and human (8) skeletal muscle, chicken polymorphonuclear granulocytes (9) and nucleoblasts (10), and mouse lymphoma cell lines Yac-1 (12, 13) and SL12 (16). Based on immunological, biochemical, and sequence analysis, it appears that the transferase, termed ART1, is glycosylphosphatidylinositol (GPI) 1 -anchored to the cell surface (8, 12). Consistent with its extracellular location, a GPIlinked muscle transferase in C2C12 mouse myotubes ADPribosylates integrin ␣7 (17). Inhibitor studies suggest that the muscle transferase may participate in the regulation of myogenesis (18).GPI-anchored transferases were found also in mouse cytotoxic T lymphocytes (CTL) and some murine T cell lymphoma and h...

Recently updated cervical screening guidelines have proposed a 5-year screening interval for women aged 30 years and older with "double-negative" Papanicolaou (Pap) and high-risk human papillomavirus (hrHPV) results (DNR); however, published US follow-up data on women with DNR tested with US Food and Drug Administration (FDA) - approved HPV testing are limited to studies from Kaiser Permanente using conventional Pap smear cytology. Between July 2005 and June 2006, 4,112 patients with DNR who were screened with computer-imaged liquid-based cytology (LBC) (ThinPrep) and Hybrid Capture 2 (HC2) hrHPV tests of LBC vial fluid were identified. Cytologic or histopathologic data were available for 3,211 patients who were followed up for a mean 44 months. Among 2,960 patients aged 30 years and older with DNR, follow-up cervical abnormalities of cervical intraepithelial neoplasia (CIN) 3 or more severe (CIN3+) were documented in 5 (0.17%), including 1 endocervical adenocarcinoma. After DNR, CIN+ diagnoses were significantly more likely in women younger than 50 years than in older women. These data are consistent with previously published US and international studies that have consistently documented low rates of histopathologic CIN3+ during years of follow-up after DNR. Large-scale nationwide data are needed to further assess the level of risk of invasive cervical cancer after DNR using different available hrHPV testing methods.

Context.-Cervical screening in the United States increasingly involves newer US Food and Drug Administration-approved cytologic methods and adjunctive highrisk human papillomavirus (hrHPV) DNA testing.Objective.-To document cervical screening test performance preceding histopathologic cervical intraepithelial neoplasia (CIN) 2/3 diagnoses.Design.-Preceding screening test results with computer-imaged, liquid-based cytology (LBC) and hrHPV results were analyzed for 2827 patients with histopathologic CIN 2/3 diagnoses.Results.-Of 2827 patients with CIN 2/3 diagnoses, 2074 (73.4%) had system LBC findings within 4 months of CIN 2/3 diagnoses: high-grade squamous intraepithelial lesion (n ¼ 862; 41.6%), low-grade squamous intraepithelial lesion (n ¼ 464; 22.4%), atypical squamous cells of undetermined significance (n ¼ 445; 21.5%), atypical squamous cells, cannot exclude high-grade squamous intraepithelial lesion (n ¼ 288; 13.9%), and atypical glandular cells/adenocarcinoma in situ (n ¼ 15; 0.7%). Of the 2827 patients, 1488 (52.6%) also had earlier system LBC results at more than 4 months to 3 years before CIN 2/3 diagnoses: one or more abnormal LBC results (n ¼ 978; 65.7%), one or more negative LBC results (n ¼ 911; 61.2%), both abnormal and negative LBC (n ¼ 401; 26.9%). Of 807 patients with hrHPV cotest results within 4 months of CIN 2/3 diagnoses, 786 (97.4%) had hrHPV þ results. Of 454 patients who also had earlier hrHPV results at more than 4 months to 3 years before CIN 2/3 diagnoses: 377 (83.0%) had one or more hrHPV þ result, 110 (24.2%) had one or more hrHPV À result, and 33 (7.3%) had both positive and negative HPV results.Conclusion.-Patients with histopathologic CIN 2/3 had recent abnormal LBC results, most often, high-grade squamous intraepithelial lesions. Among cotested patients, 97.4% (786 of 807) tested hrHPV þ . However, a significant number of patients tested during an extended period of several years had earlier negative Papanicolaou or negative HPV test results, suggesting the recent development of some CIN 2/3 lesions and supporting the value of cotesting for enhanced detection of other developing, small, inaccessible, or nondiagnostic precursor lesions.