Ankyrin repeat, one of the most widely existing protein motifs in nature, consists of 30−34 amino acid residues and exclusively functions to mediate protein−protein interactions, some of which are directly involved in the development of human cancer and other diseases. Each ankyrin repeat exhibits a helix−turn−helix conformation, and strings of such tandem repeats are packed in a nearly linear array to form helix−turn−helix bundles with relatively flexible loops. The global structure of an ankyrin repeat protein is mainly stabilized by intra- and inter-repeat hydrophobic and hydrogen bonding interactions. The repetitive and elongated nature of ankyrin repeat proteins provides the molecular bases of the unique characteristics of ankyrin repeat proteins in protein stability, folding and unfolding, and binding specificity. Recent studies have demonstrated that ankyrin repeat proteins do not recognize specific sequences, and interacting residues are discontinuously dispersed into the whole molecules of both the ankyrin repeat protein and its partner. In addition, the availability of thousands of ankyrin repeat sequences has made it feasible to use rational design to modify the specificity and stability of physiologically important ankyrin repeat proteins and even to generate ankyrin repeat proteins with novel functions through combinatorial chemistry approaches.

The forkhead-associated (FHA) domain is the only known phosphoprotein-binding domain that specifically recognizes phosphothreonine (pThr) residues, distinguishing them from phosphoserine (pSer) residues. In contrast to its very strict specificity toward pThr, the FHA domain recognizes very diverse patterns in the residues surrounding the pThr residue. For example, the FHA domain of Ki67, a protein associated with cellular proliferation, binds to an extended target surface involving residues remote from the pThr, whereas the FHA domain of Dun1, a DNA damage-response kinase, specifically recognizes a doubly phosphorylated Thr-Gln (TQ) cluster by virtue of its possessing two pThr-binding sites. The FHA domain exists in various proteins with diverse functions and is particularly prevalent among proteins involved in the DNA damage response. Despite a very short history, a number of unique structural and functional properties of the FHA domain have been uncovered. This review highlights the diversity of biological functions of the FHA domain-containing proteins and the structural bases for the novel binding specificities and multiple binding modes of FHA domains.

Forkhead-associated (FHA) domains recognize phosphothreonines, and SQ/TQ cluster domains (SCDs) contain concentrated phosphorylation sites for ATM/ATR-like DNA-damage-response kinases. The Rad53-SCD1 has dual functions in regulating the activation of the Rad53-Dun1 checkpoint kinase cascade but with unknown molecular mechanisms. Here we present structural, biochemical, and genetic evidence that Dun1-FHA possesses an unprecedented diphosphothreonine-binding specificity. The Dun1-FHA has >100-fold increased affinity for diphosphorylated relative to monophosphorylated Rad53-SCD1 due to the presence of two separate phosphothreonine-binding pockets. In vivo, any single threonine of Rad53-SCD1 is sufficient for Rad53 activation and RAD53-dependent survival of DNA damage, but two adjacent phosphothreonines in the Rad53-SCD1 and two phosphothreonine-binding sites in the Dun1-FHA are necessary for Dun1 activation and DUN1-dependent transcriptional responses to DNA damage. The results uncover a phospho-counting mechanism that regulates the specificity of SCD, and provide mechanistic insight into a role of multisite phosphorylation in DNA-damage signaling.

Aim:The present observational, cross-sectional prospective study was conducted during the period of 1 year in one of the rural health centers to study prevalence of conventional cardiovascular disease risk factors (CVRFs) in postmenopausal women.Materials and Methods:Five hundred consecutive postmenopausal women were screened for detailed information regarding common menopausal symptoms, the presence or absence of conventional CVRFs. Physical activity was measured, and dietary lifestyle was also assessed. Use of hormone replacement therapy (HRT) and other drugs were also noted. Knowledge regarding their menopause was also evaluated.Results:Mean age at menopause was 49.35 years, Mean number of menopausal symptoms was 6.70 ± 5.76, and mean duration since menopause was (MDSM = 4.70 years)). Fatigue, lack of energy (70%), cold hand and feet, rheumatology-related symptoms (60%) cold sweats, weight gain, irritability, and nervousness (50%), palpitation of heart, excitable/anxiety (30%) each were common complaints. Hypertension was diagnosed or a person was a known hypertensive (56%). Diabetes was diagnosed or a person was known diabetic in 21%, and BMI was found to be 25 kg/m2 in 78%. Truncal obesity with waist-hip ratio >0.8 in 68% females, whereas abdominal obesity with waist size >88 cm was in 60% women. Dyslipidemia was seen in 39%. It was defined by the presence of high TC (=200 mg/dL) in 30%, high LDL-c (=130 mg/dL) in 27%, low HDLc (<40 mg/dL) in 21% or high TG (=150 mg/dL) in 31%. Metabolic syndrome was present in 13% of cases. CRP was found positive in 12 out of 39 total evaluated women, and serum uric acid was found >6.5 mg/dL in 4%. Smoking (0.5%), alcohol (0%,), tobacco chewing (4%), and family history of premature heart disease (9%) were recorded. Lifestyle was active in 35%, hectic in 10%, and sedentary in 55% of postmenopausal women (PMWs). Only 5% of women were receiving HRT, 0.5% isoflavone-containing phytoestrogens, 0.4% tibolone, 24% anti-HT, 9% anti-diabetic, 8% lipid-lowering drugs, and only three patients were on anti-obesity along with dietary and lifestyle management. Out of 68 patients, who were advised for electrocardiography (ECG), 23 were found positive for ischemic changes on ECG and out of 12 women advised for treadmill test (TMT), only four were found positive for ischemic heart disease (IHD). Risk factor count of more than four was found in 11%. Over all 96% of women were affected by menopause or related problems. Only 9% were aware about their menopause, 3% for importance of lifestyle modification, weight and dietary management programs to ameliorate menopause or menopause-compounded CVRFs.Conclusion:This study showed alarmingly high prevalence of most of the conventional CVRFs, especially diabetes, hypertension, dyslipidemia, obesity, and other risk factors in postmenopausal women from rural areas.