The Journal of Immunology, Vol 143, Issue 9 2923-2928, Copyright © 1989 by American Association of Immunologists

ARTICLES

Human monoclonal anti-La antibodies. The La protein resides on a subset of Ro particles

MJ Mamula, ED Silverman, RM Laxer, L Bentur, B Isacovics and JA Hardin
Yale University School of Medicine, Department of Internal Medicine, New Haven, CT 06510.

We have addressed the problem of anti-La autoimmune responses by defining the specific binding sites of human mAb to the La protein. Two human anti-La mAb were developed; one an IgM (kappa) (designated 8G3) and the second an IgG1 (kappa) (9A5) isotype. The mAb 8G3 immunoprecipitated the La RNA and La protein from crude human cell lysates; bound the 50-kDa La protein and a 28-kDa digestion fragment in immunoblots, and recognized a small defined internal segment from the cloned La protein. In contrast, the IgG isotype (9A5) failed to precipitate native La from cell lysates but bound the same segment of digested La protein and the same polypeptide of 131 amino acids in length from the cloned La protein. Immunoprecipitation experiments performed with these mAb demonstrated that the La protein is a component of a subset of Ro particles. The data suggest that the La protein is not present on the hY RNA in the absence of the Ro polypeptide. These observations may define functional subsets or maturation states of hY RNA based on their association with Ro or Ro and La polypeptides.

This article has been cited by other articles:

				J.-C. Labbé, S. Hekimi, and L. A. Rokeach The Levels of the RoRNP-Associated Y RNA Are Dependent Upon the Presence of ROP-1, the Caenorhabditis elegans Ro60 Protein Genetics, January 1, 1999; 151(1): 143 - 150. [Abstract] [Full Text]

				R Peek, G. Pruijn, A. van der Kemp, and W. van Venrooij Subcellular distribution of Ro ribonucleoprotein complexes and their constituents J. Cell Sci., January 11, 1993; 106(3): 929 - 935. [Abstract] [PDF]