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Detection of Specific Protein Bands with Melatonin‐Like Immunoreactivity in Different Cell Lines and Human Brain Regions
Author(s) -
Lahiri Debomoy K.,
Davis Dawn,
Nurnberger John I.
Publication year - 1999
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1080/713803481
Subject(s) - melatonin , biology , epitope , pineal gland , cell culture , melatonin receptor , antibody , microbiology and biotechnology , endocrinology , immunology , genetics
The pineal hormone melatonin regulates various neural and endocrine processes involved in mammalian circadian rhythms. To understand how melatonin mediates these functions, we investigated melatonin‐like immunoreactivity (MLI) in cell extracts and human brain. In Western immunoblots, we detected highmolecular‐mass protein bands (85‐135 kDa) that specifically reacted with the anti‐melatonin antibody. The specific protein bands were present in cell extracts from the human brain and cell lines of different origins. The immunoreactive signal of the 135‐kDa protein band was highest in a neuroendocrine PC12 cell line, which was 10‐fold higher than the signal observed in any cell extracts used. The commercial antibody employed in the Western blots was further purified against serum proteins and thyroglobulins. We have previously reported that the antibody against melatonin recognizes MLI as detected by a sensitive RIA. In the present report we have detected the putative melatonin‐specific binding proteins, which could contribute to the MLI. Our results suggest that melatonin binds with specific proteins in different cellular and brain extracts, the protein(s) being maximally synthesized in PC12 cells. These results may indicate a group of yet unknown proteins sharing a melatonin‐like epitope or the presence of melatonin‐binding protein(s) that regulate availability of free melatonin, or both.