CRAYFISH ALPHA-MACROGLOBULIN AND 76 KDA PROTEIN - THEIR BIOSYNTHESIS AND SUBCELLULAR-LOCALIZATION OF THE 76 KDA PROTEIN

A 76 kDa protein from the freshwater crayfish, Pacifastacus leniusculus, which previously has been demonstrated to mediate the attachment and degranulation of crayfish haemocytes, was shown to be synthesized in the haemocytes This was demonstrated by immunoprecipitation of [S-35]methionine-labelled haemocyte preparations. With the use of immunogold staining and electron microscopy it was shown that this protein is localized to the granules of both the semigranular and granular haemocytes, suggesting that after synthesis, the 76 kDa protein is deposited into these organelles. One protein present in the plasma of freshwater crayfish, the alpha-macroglobulin-like proteinase inhibitor, was also found to be synthesized in the haemocytes.