Molecular cloning of a P-type Ca2+-ATPase from the halotolerant algaDunaliella bioculata

✍ Scribed by Birgit C. Raschke; Andreas H. Wolf

• Publisher: Springer-Verlag
• Year: 1996
• Tongue: English
• Weight: 1015 KB
• Volume: 200
• Category: Article
• ISSN: 0032-0935
• DOI: 10.1007/bf00196652

✦ Synopsis

We have determined the complete primary structure of a putative P-type CaZ+-ATPase from the unicellular, halotolerant alga Dunaliella bioculata. The protein (DBCA1) with a calculated molecular mass of 114 kDa and eight or ten putative transmembrane segments contains all amino acid motifs specific to the family of P-type ATPases. Highest homology scores were obtained by comparison with (sarco)endoplasmic reticulum-type plant and animal Ca2+-ATPases (54% identity, 70% similarity). In addition, all amino acids shown to be essential for Ca 2 § transport in animal sarcoplasmic reticulum Ca2+-ATPases are preserved in DBCA1. Significantly lower homologies were found with animal plasma membrane Ca 2 +-ATPases (33% identity, 55 % similarity), and the carboxyterminus of DBCA1 gave no indications of possible calmodulin-binding sites, characteristic of those enzymes. It is assumed that DBCA1 is a representative of the endomembrane class of Ca 2+-ATPases. In Northern blot experiments with polyadenylated RNA, a 3.7-kb transcript was detected at levels which were very low compared with those of the plasma membrane H+-ATPase from D.