Fujii G et al. (1991), Deduced primary structure of a Xenopus proteaso...

XB-ART-24611

Biochem Biophys Res Commun 1991 Aug 15;1783:1233-9.

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Deduced primary structure of a Xenopus proteasome subunit XC3 and expression of its mRNA during early development.

Fujii G , Tashiro K , Emori Y , Saigo K , Tanaka K , Shiokawa K .

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Proteasome is a non-lysosomal proteinase complex ubiquitously distributed in eukaryotic cells. We isolated here the cDNA clone for one of the proteasome subunits (XC3) from Xenopus ovary cDNA libraries using rat RC3 cDNA as a prove. The cDNA is 885 bp long and encodes 234 amino acids. The deduced amino acid sequence is highly homologous (95.3%) to those of rat RC3 and human HC3 subunits. The mRNA for XC3 is one of the maternal mRNAs and detected at all the embryonic stages investigated, but its level changes in a characteristic way especially at the gastrula stage. We suggest that the highly conserved XC3 subunit plays an essential role in proteasome function and also that during Xenopus embryogenesis mRNA for XC3 subunit is replaced from maternal to newly-synthesized one probably around the gastrula stage.

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Species referenced: Xenopus
Genes referenced: psma2

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	Fig. 1. Nudeotide sequence and deduced amino acid sequence of the cDNA for Xenopus proteasome subunit (XC3). Deduced amino add sequence is indicated in one letter. Open square Is placed at the sequence which is identical to the nuclear translocetion signal. Open drde indicates the tyrosine residue which could be phosphorylated by tyrosine kfnase.
	Fig. 2. A comparison of deduced amino acid sequence of Xenopus proteasome subunit XC3 with those of rat RC3 and human HC3. Dashes are for amino acid residues which are identical to those of Xenopus.
	Fig. 3. Expression of proteasome subunit XC3 mRNA during the embryogenesis of Xenopus laevis. Total RNAs equivalent for 1.5 embryos at various stages were analyzed by Northern blot hybridization using XC3 cDNA as a prove. Lane 1, unfertilized egg; lane 2, stage 3 (16 cell-stage) ; lane 3, stage 6 (late cleavage) ; lane 4, stage 8.5 (midbiastuia) ; lane 5, stage 10 (midgastrula) jane 6, stage 11 (late gastrula) ; lane 7, stage 15 (early neurula) ; lane 8, stage 20 (late neunrla) ; lane 9, stage 23 (tailbud) ; lane 10, stage 25 (swimming tadpole). Arrows indicate the positions of 28 S and 18 S ribosomal RNA.