Figure 1 Stucture of leptin and defective leptin proteins. The gene for leptin in both humans and rodents encodes a 167amino acid protein with an amino terminal secretory signal sequence of21 amino acids (4). The signal sequence is cleaved during protein processing and leptin circulates in the blood as a 16 kDa protein. In C57BL/61 ob/ob mice a T to C substitution in the first position of codon 105 changes an arginine to a premature stop codon. Two families with mutations in the LEP gene have been identified. In family No.1, a guanine nucleotide in codon 133 is deleted, which results in a frameshift and the synthesis of a truncated leptin protein (91). In the second family a C to T substitution in the first base of codon 105 changes arginine to tryptophan (92). The mutant leptin protein in the ob/ob mouse and in both families is not secreted but is degraded in the adipocyte.
|Original language||English (US)|
|Title of host publication||Handbook of Obesity|
|Subtitle of host publication||Clinical Applications|
|Number of pages||21|
|ISBN (Print)||0824747739, 9780824747732|
|State||Published - Jan 1 2003|
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