The mouse tubby mutation is the cause of maturity-onset obesity, insulin resistance and sensory deficits. This mutation maps to a gene, tub [1,2], which codes for a protein that belongs to a family which currently consists of the following members:

• Mammalian tub, an hydrophilic protein of about 500 residues, which could be involved in the hypothalamic regulation of body weight.
• Human protein TULP1 [3] is involved in retinis pigmentosa 14 (RP14), a retinal degeneration disease.
• Human protein TULP2 [3].
• Mammalian protein TULP3 [4].
• Mouse protein p4-6 whose function is not known.
• Caenorhabditis elegans hypothetical protein F10B5.4.
• Several fragmentary sequences from plants, Drosophila and human ESTs.

While the N-terminal part of these protein is not conserved in length nor in the sequence, the C-terminal 250 residues are highly conserved. We therefore selected two regions in the C-terminal part as signature patterns. The second region is located at the C-terminal extremity and contains a penultimate cysteine residue that could be critical to the normal functioning of these proteins.