TY - JOUR
T1 - Human calumenin localizes to the secretory pathway and is secreted to the medium
AU - Vorum, Henrik
AU - Hager, Henrik
AU - Christensen, Birgitte M.
AU - Nielsen, Søren
AU - Honoré, Bent
N1 - Copyright 1999 Academic Press.
PY - 1999/5/1
Y1 - 1999/5/1
N2 - Calumenin belongs to a family of multiple EF-hand proteins that include reticulocalbin, ERC-55, and Cab45. Reticulocalbin and ERC-55 localize to the ER due to a C-terminal HDEL retrieval signal. Cab45 contains a HEEF C-terminal sequence and is localized to the Golgi apparatus. The murine homologue of calumenin is reported to be present in the ER due to a C-terminal HDEF retrieval signal. The human homologue differs from the murine at 7 amino acid positions but the HDEF signal is conserved. However, in the cultured human cell lines, HaCaT keratinocytes, normal and transformed MRC-5 fibroblasts, as well as in transfected COS-1 cells, human calumenin could be demonstrated in the ER as well as in the Golgi complex. Especially in MRC-5 cells, a certain heterogeneity was observed, with some of the cells having calumenin localized solely to the ER while in other cells calumenin could be demonstrated in the ER as well as in the Golgi complex. Immunoelectron microscopy of placental syncytiotrophoblast cells showed that a substantial fraction of calumenin is localized in close association with the ER membrane. In addition, the protein may be recovered from the medium of cultured cells in an endoglycosidase H-resistant form, suggesting that the glycosylated protein has been further modified in the Golgi apparatus and secreted to the medium. Udgivelsesdato: 1999-May-1
AB - Calumenin belongs to a family of multiple EF-hand proteins that include reticulocalbin, ERC-55, and Cab45. Reticulocalbin and ERC-55 localize to the ER due to a C-terminal HDEL retrieval signal. Cab45 contains a HEEF C-terminal sequence and is localized to the Golgi apparatus. The murine homologue of calumenin is reported to be present in the ER due to a C-terminal HDEF retrieval signal. The human homologue differs from the murine at 7 amino acid positions but the HDEF signal is conserved. However, in the cultured human cell lines, HaCaT keratinocytes, normal and transformed MRC-5 fibroblasts, as well as in transfected COS-1 cells, human calumenin could be demonstrated in the ER as well as in the Golgi complex. Especially in MRC-5 cells, a certain heterogeneity was observed, with some of the cells having calumenin localized solely to the ER while in other cells calumenin could be demonstrated in the ER as well as in the Golgi complex. Immunoelectron microscopy of placental syncytiotrophoblast cells showed that a substantial fraction of calumenin is localized in close association with the ER membrane. In addition, the protein may be recovered from the medium of cultured cells in an endoglycosidase H-resistant form, suggesting that the glycosylated protein has been further modified in the Golgi apparatus and secreted to the medium. Udgivelsesdato: 1999-May-1
KW - Antibody Specificity
KW - Calcium-Binding Proteins
KW - Cell Compartmentation
KW - Endoplasmic Reticulum
KW - Fluorescent Antibody Technique, Indirect
KW - Glycosylation
KW - Golgi Apparatus
KW - Humans
KW - Microscopy, Immunoelectron
KW - Recombinant Proteins
U2 - 10.1006/excr.1999.4431
DO - 10.1006/excr.1999.4431
M3 - Journal article
C2 - 10222138
SN - 0014-4827
VL - 248
SP - 473
EP - 481
JO - Experimental Cell Research
JF - Experimental Cell Research
IS - 2
ER -