The Treacher Collins Syndrome (TCOF1) Gene Product, Treacle, is Targeted to the Nucleolus by Signals in Its C-Terminus

• Published in: Human molecular genetics 1998-11, Vol.7 (12), p.1947-1952
• Main Authors: Winokur, Sara T., Shiang, Rita
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Biological and medical sciences; Cell Nucleolus - chemistry; COS Cells - chemistry; COS Cells - cytology; COS Cells - metabolism; Diseases of the osteoarticular system; Green Fluorescent Proteins; Humans; Luminescent Proteins - genetics; Malformations and congenital and or hereditary diseases involving bones. Joint deformations; Mandibulofacial Dysostosis - metabolism; Medical sciences; Mice; Microscopy, Fluorescence; Molecular Sequence Data; Nuclear Proteins - analysis; Nuclear Proteins - chemistry; Nuclear Proteins - genetics; Phosphoproteins - analysis; Phosphoproteins - chemistry; Phosphoproteins - genetics; Recombinant Fusion Proteins - genetics; Sequence Homology, Amino Acid; Transfection
• ISSN: 0964-6906; 1460-2083
• DOI: 10.1093/hmg/7.12.1947

The TCOF1 gene product, treacle, responsible for the craniofacial disorder Treacher Collins syndrome, has been predicted to be a member of a class of nucleolar phosphoproteins based on its primary amino acid sequence. Treacle is a low complexity protein with ten repeating units of acidic and basic residues, each of which contains a large number of putative casein kinase 2 and protein kinase C phosphorylation sites. In addition, the C-terminus of treacle contains multiple putative nuclear localization signals. The overall structure of treacle, as well as sequence similarity to several nucleolar phosphoproteins, predicts that treacle is a member of this class of proteins. Using green fluorescent protein fusion constructs with the full-length and deleted domains of the murine homolog of treacle, we demonstrate that the cellular localization of treacle is nucleolar. This localization is mediated by the last 41 residues of the C-terminus (residues 1262–1302). At least two functional nuclear localization signals have been identified in the protein, one between residues 1176 and 1270 and the second within the last 32 residues of the protein (1271–1302). The nucleolar localization signal is disrupted by two constructs that split the C-terminal region between residues 1270 and 1271. This study provides the first direct analysis of treacle and demonstrates that the protein involved in TCOF1 is a nucleolar protein.