DEVELOPMENTAL-CHANGES OF THE 26-S-PROTEASOME IN ABDOMINAL INTERSEGMENTAL MUSCLES OF MANDUCA-SEXTA DURING PROGRAMMED CELL-DEATH

cDNA clone MS73 codes for an ATPase that is a regulatory subunit of the 26 S proteasome, Reverse transcriptase polymerase chain reaction analysis demonstrates that the expression of the gene dramatically increases in the pre-eclosion period, Western analyses show increases in other related ATPases including MS73, MSS1, and mts2 but not TBP1. A similar increase in the 30-kDa subunit of the 20 S proteasome occurs. There are accompanying large changes in the peptidase activities of the 26 S proteasome. Relative to the 30-kDa subunit, there is no change in MSS1 and MS73, a 3-fold increase in mts2, and a B-fold decline in TBP1. A large increase in the concentration of 26 S proteasomes together with extensive regulatory reprogramming may facilitate rapid muscular proteolysis.