Serologic Demonstration of the Albuminoid Nature of the B700 Murine Melanoma Antigen

Gersten, Douglas M.; Bijwaard, Karen E.; Walden, Thomas L.; Hearing, Vincent J.

doi:10.3181/00379727-197-43261

Cited by 2 publications

(2 citation statements)

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“…In this respect, it is worth mentioning that CRT is up-regulated during proliferation, and high levels of CRT expression were detected in B16 melanoma cells (Gersten et al, 1990). Noteworthy, the promoter region of CRT contains a retinoblastoma control element (Krause and Michalak, 1997).…”

Section: Discussionmentioning

confidence: 99%

Delayed Activation of the Store-operated Calcium Current Induced by Calreticulin Overexpression in RBL-1 Cells

Fasolato

Pizzo

Pozzan

1998

MBoC

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Calreticulin (CRT) is a high-capacity, low-affinity Ca 2ϩ -binding protein located in the lumen of the endoplasmic reticulum (ER) of all eukaryotic cells investigated so far. Its high level of conservation among different species suggests that it serves functions fundamental to cell survival. The role originally proposed for CRT, i.e., the main Ca 2ϩ buffer of the ER, has been obscured or even casted by its implication in processes as diverse as gene expression, protein folding, and cell adhesion. In this work we seek the role of CRT in Ca 2ϩ storing and signaling by evaluating its effects on the kinetics and amplitude of the store-operated Ca 2ϩ current (I CRAC ). We show that, in the rat basophilic leukemia cell line RBL-1, overexpression of CRT, but not of its mutant lacking the high-capacity Ca 2ϩ -binding domain, markedly retards the I CRAC development, however, only when store depletion is slower than the rate of current activation. On the contrary, when store depletion is rapid and complete, overexpression of CRT has no effect. The present results are compatible with a major Ca 2ϩ -buffering role of CRT within the ER but exclude a direct, or indirect, role of this protein on the mechanism of I CRAC activation. INTRODUCTIONThe endoplasmic reticulum (ER) is the most relevant source of mobilizable Ca 2ϩ in mammalian cells. The free intralumenal Ca 2ϩ concentration has been estimated to range between 0.2 and 2 mM (Hofer et al., 1995;Montero et al., 1995Montero et al., , 1997Hofer and Schulz 1996;Miyawaki et al., 1997). Among Ca 2ϩ -binding proteins that are known to be resident ER proteins, calreticulin (CRT) is among the most abundant (Lytton and Nigam, 1992) and may account for up to ϳ1-2% of total ER proteins. CRT has been considered the best candidate to function as an ER Ca 2ϩ buffer, because it mostly resembles calsequestrin, the well-known Ca 2ϩ -storing protein of the sarcoplasmic reticulum. The overall biochemical and functional properties of CRT have been thoroughly characterized. CRT is a soluble, small glycoprotein of 417 amino acids that contains three functional domains (Nash et al., 1994;Meldolesi et al., 1996;Krause and Michalak, 1997). In particular, the C-terminal domain binds Ca 2ϩ with high capacity (25-50 mol/mol of protein) and low affinity (K d Х 0.5-1 mM) through a negatively charged region (Ostwald and MacLennan, 1974;Macer and Koch, 1988;Damiani et al., 1989;Treves et al., 1990).It has been shown previously that CRT overexpressed by transient transfection in HeLa cells is specifically targeted to the ER and selectively increases the Ca 2ϩ content of thapsigargin-sensitive stores . Along the same line, treatment of cells with antisense oligonucleotides reduces the peak level of [Ca 2ϩ ] i increase caused by receptor stimulation (Liu et al., 1994). Recent findings, however, have challenged the role of CRT as a major Ca 2ϩ -storing protein (Meldolesi et al., 1996;Krause and Michalak, 1997). The effect on Ca 2ϩ homeostasis has in fact been suggested to be independent of the C domain...

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Section: Discussionmentioning

confidence: 99%

Delayed Activation of the Store-operated Calcium Current Induced by Calreticulin Overexpression in RBL-1 Cells

Fasolato

Pizzo

Pozzan

1998

MBoC

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“…There is as yet no animal model for studying urinary excretion of melanoma antigens; the subject of cross species melanoma antigens has been recently reviewed (Gersten and Hearing, 1992a). The complete sequence of I3700 is not yet known, but amino acid analysis (Marchalonis et al, 1984), N-terminal sequence (Marchalonis et al, 1984), and serological cross-reactivity studies (Gersten et al, 1991) place B700 in the serum albumin fam-ily. Two functional attributes of serum albumin which we have studied have been conserved in B700.…”

Section: Introductionmentioning

confidence: 99%

Proteinuria of B700, a 67 kD Albumin‐like Melanoma‐Specific Antigen

Walden

Farzaneh

Hearing

et al. 1992

Pigment Cell Research

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B700 is a murine melanoma antigen that is closely related to, but distinct from, serum albumin. The present study examined the metabolic fate and anatomic distribution of radioiodinated B700 and mouse serum albumin (MSA) administered s.c. to mice. In blood, both proteins were associated with the plasma fraction where the halflife of B700, a glycoprotein, was 0.5 days, compared to 2.7 days for MSA. Of particular interest was the observation that B700, a 67 kD anionic protein, was excreted primarily in urine. The selective B700-proteinuria did not alter urinary volumes or produce hematuria or edema. SDS-polyacrylamide gel electrophoresis and western blot analysis using the H-2-3-3 B700-specific monoclonal antibody revealed that B700 proteinuria occurred in B-16 murine melanoma bearing animals but not in control mice. These studies demonstrate that the tumor-bearing host readily distinguishes between very similar normal protein (MSA) and tumor-associated antigen (B700) molecules and processes them differently.

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Serologic Demonstration of the Albuminoid Nature of the B700 Murine Melanoma Antigen

Cited by 2 publications

References 6 publications

Delayed Activation of the Store-operated Calcium Current Induced by Calreticulin Overexpression in RBL-1 Cells

Delayed Activation of the Store-operated Calcium Current Induced by Calreticulin Overexpression in RBL-1 Cells

Proteinuria of B700, a 67 kD Albumin‐like Melanoma‐Specific Antigen

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