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Immunocytochemical localization of the multicatalytic proteinase (Proteasome) in crustacean striated muscles
Author(s) -
Beyette Jill R.,
Mykles Donald L.
Publication year - 1992
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.880150907
Subject(s) - staining , immunocytochemistry , cytoplasm , biology , intracellular , cytosol , colocalization , microsome , extracellular , differential centrifugation , biochemistry , organelle , microbiology and biotechnology , enzyme , endocrinology , genetics
Multicatalytic proteinase (MCP) is thought to play a central role in the processing and turnover of intracellular proteins in eukaryotic cells. Immunocytochemistry was used to determine the intracellular distribution of the MCP in the claw muscles of the land crab, Gecarcinus lateralis , and the claw and abdominal muscles of the American lobster, Homarus americanus . Cryosections were stained with an affinity‐purified polyclonal antibody to lobster MCP that cross‐reacted with the land crab enzyme. Two types of staining were observed: a diffuse cytoplasmic staining, and a dense aggregate staining primarily associated with invaginations of the cell membrane. The cytoplasmic staining appeared reticulated in favorable transverse sections due to a preferential localization of MCP to the intermyofibrillar space. The aggregate staining was associated with neither nuclei nor mitochondria, since stains specific for these organelles (Hoechst stain and nicotinamide adenine dinucleotide diaphorase histochemistry, respectively) did not colocalize with the aggregates. Trypsinlike peptidase activities of isolated microsomal and postmicrosomal fractions indicated that less than 1% of the total MCP was associated with the microsomal fraction. Immunoprecipitaion of the same fractions confirmed the presence of MCP in the microsomes as well as in the cytosol. These results suggest that the MCP is primarily associated with cytoplasmic components; the aggregate staining may result from the association of the MCP with cellular membrane systems. © 1992 John Wiley & Sons, Inc.