ABSTRACT
During transcription elongation, eukaryotic RNA polymerase II (Pol II) must contend with the barrier presented by nucleosomes. The conserved Spt4-Spt5 complex has been proposed to regulate elongation through nucleosomes by Pol II. To help define the mechanism of Spt5 function, we have characterized proteins that coimmunopurify with Spt5. Among these are the general elongation factors TFIIF and TFIIS as well as Spt6 and FACT, factors thought to regulate elongation through nucleosomes. Spt5 also coimmunopurified with the mRNA capping enzyme and cap methyltransferase, and spt4 and spt5 mutations displayed genetic interactions with mutations in capping enzyme genes. Additionally, we found that spt4 and spt5 mutations lead to accumulation of unspliced pre-mRNA. Spt5 also copurified with several previously unstudied proteins; we demonstrate that one of these is encoded by a new member of the SPT gene family. Finally, by immunoprecipitating these factors we found evidence that Spt5 participates in at least three Pol II complexes. These observations provide new evidence of roles for Spt4-Spt5 in pre-mRNA processing and transcription elongation.
Subject(s)
Chromosomal Proteins, Non-Histone , RNA, Messenger/metabolism , Saccharomyces cerevisiae Proteins/metabolism , Transcription Factors, General/metabolism , Transcriptional Elongation Factors/metabolism , Carrier Proteins/metabolism , Cell Cycle Proteins/metabolism , Histone Chaperones , Methyltransferases/isolation & purification , Methyltransferases/metabolism , Mutation , Nuclear Proteins/genetics , Nuclear Proteins/metabolism , Nucleotidyltransferases/isolation & purification , Nucleotidyltransferases/metabolism , RNA Polymerase II/isolation & purification , RNA Polymerase II/metabolism , RNA Precursors , RNA Processing, Post-Transcriptional , RNA Splicing , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae Proteins/genetics , Transcription Factors/metabolism , Transcription Factors, General/isolation & purification , Transcription Factors, TFII/isolation & purification , Transcription Factors, TFII/metabolism , Transcriptional Elongation Factors/genetics , Transcriptional Elongation Factors/isolation & purificationABSTRACT
STUDY DESIGN: Muscle tension with tenderness may be localized or generalized as in fibromyalgia. Wartenberg's pendulum test might be appropriate for quantitating muscle damping, at least in generalized cases. OBJECTIVE: Damping values provide a quantitative measure of muscle tension and of the response to various treatments. SUMMARY OF THE BACKGROUND DATA: According to recent anatomic and experimental works, intrafusal muscle fibers are double-innervated by gamma motoneurons and sympathetic fibers. With electromyograph recording, the activity of extrafusal fibers and gamma motoneurons (reflexes) can be assessed and separated from the action of the sympathetic system. METHODS: An electrogoniometer registers the movements of the freely swinging leg. On the oscilloscope, the patient's nodular curve is compared with an ideal calculated dampened curve to find the damping value. Electromyograph surface electrodes from the knee extensors and flexors detect the activity of extrafusal fibers and the occurrence of reflexes. RESULTS: In longstanding severe fibromyalgia, damping values are almost always elevated, at least in one leg. Half or more of patients with chronic lumbago and cervical syndrome present with increased damping. The surface electromyograph remains silent (in contrast to spastic patients). CONCLUSION: The findings support the hypothesis that muscle tension in rheumatic patients results from overactivity of the sympathetic system (or part of it). Even in clinically localized pain syndromes, muscle damping is often increased in the legs. The test is valuable for quantitating muscle tension and the effectiveness of therapeutic methods.