Alternative exon usage and processing of the major histocompatibility complex-encoded proteasome subunits.
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Fruh K, Yang Y, Arnold D, Chambers J, Wu L, Waters JB, Spies T, Peterson PA
Alternative exon usage and processing of the major histocompatibility complex-encoded proteasome subunits.
J Biol Chem. 1992 Nov 5;267(31):22131-40.
- PubMed ID
- 1429565 [ View in PubMed]
- Abstract
The finding that two subunits of the proteasome, LMP2 and LMP7, are encoded in the major histocompatibility complex (MHC) has linked the proteasome which represents a major extralysosomal proteolytic system to the processing of intracellular antigens. Here we describe a second form of the human LMP7 cDNA, LMP7-E2, which has been identified during the characterization of novel genes in the MHC. The analysis of the genome organization of LMP7 revealed that LMP7-E1 and LMP7-E2 arise by alternative exon usage. Using specific antibodies against LMP2 and LMP7, we show that they are co-expressed with class I MHC molecules as well as a putative peptide transporter. The polypeptides encoded by LMP7 and LMP2 undergo proteolytic processing when incorporated into proteasomes, and the LMP7 precursor is derived mainly from LMP7-E2. Furthermore, our data suggest that LMP7 and LMP2 are mutually dependent for their incorporation into the proteasomal complex.