Universal and specific characteristics of nucleus functioning in the systems of non-related languages

The article deals with one of the most important parts in any intonation group - the nucleus, and its role in expressing the informational sentence structure in English, Russian and Spanish. It reports on the means of signaling utterance focus in each of the languages as well as comparative analyses between them. The facts described provide foundation for further research of nucleus location and its choice in non-native English speech of Russian and Spanish-speaking learners of English.