High impact information on RCN2

• E6BP is identical to a putative calcium-binding protein, ERC-55, that appears to be localized in the endoplasmic reticulum [1].
• The ERC-55 protein comprises an amino-terminal signal sequence followed by six copies of the EF-hand Ca2+ binding motif [2].
• Ca2+ binding was demonstrated directly for recombinant ERC-55 using the 45Ca2+ overlay technique [2].
• The carboxyl-terminal sequence His-Asp-Glu-Leu (HDEL) is required for retention of ERC-55 in the ER [2].
• These mutants also distinguish transcriptional activation from E6-AP and E6BP binding [3].

Biological context of RCN2

• Assignment of the gene for ERC-55 (RCN2) to human chromosome band 15q22.33-->q24.1 by in situ hybridization [4].
• Confirmatory PCR and FISH mapping of the der(15) showed loss of chromosome material proximal to the breakpoint on chromosome 15, containing the PSTPIP1 and RCN2 genes [5].

Other interactions of RCN2

• Calumenin belongs to a family of multiple EF-hand proteins that include the ER localized proteins reticulocalbin and ERC-55 and the Golgi localized Cab45 [6].
• The predicted C-terminal region also appears to contain a sixth EF-hand calcium-binding domain, which suggests that PfERC is related to previously reported ER-localized calcium-binding proteins, namely reticulocalbin and ERC-55 (Ozawa M. J. Biochem. 1995;117:1113-1119; Weis K, Griffiths G, Lamond AI. J. Biol. Chem. 1994;269:19142-19150) [7].

Analytical, diagnostic and therapeutic context of RCN2

• Comparative sequence analysis indicates that ERC-55, together with the recently identified protein reticulocalbin (Ozawa and Muramatsu, 1993), constitute a new subfamily of the EF-hand superfamily of Ca(2+)-binding proteins that are specifically located in the ER [2].
• We mapped mutants with moderate activity in the biological assay that lacked the ability to bind to E6BP and a mutant that showed high biological activity with only marginal binding to E6BP [8].

References