Characterization of the protein moiety of U7 small nuclear RNP particles.

U7 snRNP particles contain a set of seven proteins with molecular weights in the range of 13.5 to 50 kD. One protein with a molecular weight of 18 kD carried the antigenic determinant responsible for the interaction of U7 snRNPs with autoantibodies from patients with connective tissue diseases. It is suggested that U7 RNA is associated with proteins representing a ribonucleoprotein particle analogous to U1, U2, U4, U5 and U6 snRNPs.