PREFERENTIAL EXPRESSION OF THE CDNA-ENCODING THE PROTEASOME SUBUNIT DURING THE GROWTH DIFFERENTIATION TRANSITION OF DICTYOSTELIUM CELLS/

A proteasome subunit-1 gene (DAPS-1) was isolated as one preferentiall y expressed during the transition from growth to differentiation in Di ctyostelium discoideum cells, using the differential display method, T he DAPS-1 cDNA sequence with a length of 882 bp encodes a protein (Mr. 23.4 kDa) consisting of 213 amino acids, The deduced amino acid seque nce of DAPS-1 showed 61% and 58% identity to the proteasome subunit Y of Xenopus laevis and Homo sapiens, respectively and 48% and 47% ident ity to the proteasome subunit LMP2 of Homo sapiens and Orizas latipes, respectively, Northern analysis revealed that a 1.0 kb of DAPS-1 mRNA is predominantly expressed during the early stage of differentiation induced by starvation, This seems to indicate that the DAPS-1 protein may be involved in proteolysis coupled with active exchange of the cel lular protein composition during the phase-shift of Dictyostelium cell s from the proliferative to differentiated state. (C) 1998 Academic Pr ess.