In this task, you're given a paragraph from the research paper and your task is to generate a suitable title for the research paper based on the given paper. Under 100 words is a good title length.

The Sec7 domain ADP-ribosylation factor (Arf) guanine nucleotide exchange factors (GEFs) are found in all eukaryotes, and are involved in membrane remodeling processes throughout the cell. This review is focused on members of the GBF/Gea and BIG/Sec7 subfamilies of Arf GEFs, all of which use the class I Arf proteins (Arf1-3) as substrates, and play a fundamental role in traYcking in the endoplasmic reticulum (ER)-Golgi and endosomal membrane systems. Members of the GBF/Gea and BIG/Sec7 subfamilies are large proteins on the order of 200 kDa, and they possess multiple homology domains. Phylogenetic analyses indicate that both of these subfamilies of Arf GEFs have members in at least Wve out of the six eukaryotic supergroups, and hence were likely present very early in eukaryotic evolution. The homology domains of the large Arf1 GEFs play important functional roles, and are involved in interactions with numerous protein partners. The large Arf1 GEFs have been implicated in several human diseases. They are crucial host factors for the replication of several viral pathogens, including poliovirus, coxsackievirus, mouse hepatitis coronavirus, and hepatitis C virus. Mutations in the BIG2 Arf1 GEF have been linked to autosomal recessive periventricular heterotopia, a disorder of neuronal migration that leads to severe malformation of the cerebral cortex. Understanding the roles of the Arf1 GEFs in membrane dynamics is crucial to a full understanding of traYcking in the secretory and endosomal pathways, which in turn will provide essential insights into human diseases that arise from misregulation of these pathways.
Large Arf1 guanine nucleotide exchange factors: evolution, domain structure, and roles in membrane traYcking and human disease

with the pathological structure of BPD, as seen in the lungs of preterm infants who died and in animal models (3, 7). As the authors note, this study was limited in that the subjects with BPD were stable outpatients younger than 3 years who did not require oxygen therapy at the time of the study. Whether their findings hold true in infants with persistent severe BPD, including those with chronic ventilator-dependent hypoxemic respiratory failure, is not clear. In addition, BPD classification was based on clinical decision making, rather than a physiologic assessment such as the oxygen reduction test (11). In an earlier article, members of this group studied DL CO and its components, DM and Vc, in full-term infants without lung disease and showed that DL CO and Vc (but not DM) correlated with the level of proangiogenic circulating hematopoietic stem/progenitor cells (pCHSPCs) (12). However, this study did not include preterm infants with or without BPD. Both pCHSPCs, also referred to as circulating progenitor cells, as well as late-outgrowth endothelial colony-forming cells, are decreased in the cord blood of preterm infants who later develop moderate or severe BPD (13, 14) . Together, these findings suggest that early disruptions in the number and function of angiogenic progenitor cells, possibly by maternal complications of pregnancy known to be associated with BPD risk, may lead to impaired development of the pulmonary vasculature and sustained impaired gas exchange in preterm infants with BPD. This study shows how a physiologic assessment, such as infant pulmonary function testing, may be used in the clinical setting to provide an estimation of impaired gas exchange in preterm infants with varying degrees of lung injury. Combining functional assays such as this with measurement of pCHSPCs and other angiogenic biomarkers in the cord blood, as well as novel imaging techniques such as quantitative pulmonary magnetic resonance imaging (15), will lead to improved disease phenotyping of preterm infants at risk for BPD. Given the spectrum of disease severity among infants with severe BPD (as determined by the currently accepted diagnostic criteria), novel methods such as these will help identify preterm neonates more accurately, permit targeted therapies for the most severely affected infants, and provide quantitative evidence of the efficacy of these interventions in young children after preterm birth (16). n
Jobe AH, Bancalari E. Bronchopulmonary dysplasia

Nonstructural protein 3 of the severe acute respiratory syndrome (SARS) coronavirus includes a "SARS-unique domain" (SUD) consisting of three globular domains separated by short linker peptide segments. This work reports NMR structure determinations of the C-terminal domain (SUD-C) and a two-domain construct (SUD-MC) containing the middle domain (SUD-M) and the C-terminal domain, and NMR data on the conformational states of the N-terminal domain (SUD-N) and the SUD-NM two-domain construct. Both SUD-N and SUD-NM are monomeric and globular in solution; in SUD-NM, there is high mobility in the two-residue interdomain linking sequence, with no preferred relative orientation of the two domains. SUD-CadoptsafrataxinlikefoldandhasstructuralsimilaritytoDNA-binding domains of DNA-modifying enzymes. The structures of both SUD-M (previously determined) and SUD-C (from the present study) are maintained in SUD-MC, where the two domains are flexibly linked. Gelshift experiments showed that both SUD-C and SUD-MC bind to singlestranded RNA and recognize purine bases more strongly than pyrimidine bases, whereby SUD-MC binds to a more restricted set of purine-containing RNA sequences than SUD-M. NMR chemical shift perturbation experiments with observations of 15 N-labeled proteins further resulted in delineation of RNA binding sites (i.e., in SUD-M, a positively charged surface area with a pronounced cavity, and in SUD-C, several residues of an anti-parallel β-sheet). Overall, the present data provide evidence for molecular mechanisms involving the concerted actions of SUD-M and SUD-C, which result in specific RNA binding that might be unique to the SUD and, thus, to the SARS coronavirus.

SARS Coronavirus Unique Domain: Three-Domain Molecular Architecture in Solution and RNA Binding