Abstract
We have characterized a cDNA clone that encodes a protein related to the 70 kd heat shock protein, but is expressed in normal rat liver. This protein has a hydrophobic leader and is secreted into the endoplasmic reticulum. We show that it is identical with two previously described proteins: GRP78, whose synthesis is induced by glucose starvation, and BiP, which is found bound to immunoglobulin heavy chains in pre-B cells. This protein, which is abundant in antibody-secreting cells, can be released from heavy chains by ATP, a reaction analogous to the release of hsp70 from heat shocked nuclear structures. We propose a specific role for this protein in the assembly of secreted and membrane-bound proteins.
MeSH terms
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Adenosine Triphosphate / physiology
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Animals
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Antibody-Producing Cells / metabolism
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Carrier Proteins / metabolism*
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Cloning, Molecular
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DNA / genetics
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Endoplasmic Reticulum / metabolism*
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HSP70 Heat-Shock Proteins*
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Heat-Shock Proteins / isolation & purification*
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Heat-Shock Proteins / metabolism
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Immunoglobulin Heavy Chains / isolation & purification*
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Immunoglobulin Heavy Chains / metabolism
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Membrane Proteins / isolation & purification*
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Membrane Proteins / metabolism
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Molecular Weight
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Protein Sorting Signals / physiology
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Rats
Substances
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Carrier Proteins
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HSP70 Heat-Shock Proteins
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Heat-Shock Proteins
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Immunoglobulin Heavy Chains
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Membrane Proteins
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Protein Sorting Signals
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glucose-regulated proteins
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Adenosine Triphosphate
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DNA