FBtr0071140_1 FBtr0071349_3 FBtr0074767_3 FBtr0077227_1 FBtr0077747_1 FBtr0077737_2 FBtr0079037_2 FBtr0079006_1 FBtr0079695_3 FBtr0080133_1 FBtr0080489_1 FBtr0080803_5 FBtr0081102_1 FBtr0081122_2 FBtr0088817_5 FBtr0088610_3 FBtr0087829_3 FBtr0091650_2 FBtr0087678_3 FBtr0087140_1 FBtr0086701_1 FBtr0086654_7 FBtr0091786_1 FBtr0071680_7 FBtr0071680_5 FBtr0071680_4 FBtr0071676_1 FBtr0071672_1 FBtr0073063_4 FBtr0074315_3 FBtr0076348_2 FBtr0076203_3 FBtr0076213_1 FBtr0074991_5 FBtr0078767_1 FBtr0082829_3 FBtr0082871_2 FBtr0083570_4 FBtr0084138_3 FBtr0084211_1 FBtr0084782_2 FBtr0084877_1 FBtr0084974_2 FBtr0085563_1 CG18624 7C2-7C2 CG12664 8C11-8C13 CG12788/CG17767b 18D3-18D7 CG33713/CG33714b 19F4-19F4 CG3240 23A1-23A1 CG9960/CG9958b 23A3-23A3 CG31917 25C1-25C1 CG31919/CG33995b 25C1-25C1 CG18042 29D4-29D5 CG7400 31F4-31F5 CG16974 34A8-34A8 CG4824 35E2-35E2 CG17325 37A4-37A5 CG10570 37A4 CG11508 44B3-44B3 CG8026 45B3-45B3 CG17759 49B8-49B9 CG33671/CG33672b 49B10-49B10 CG6191 50B3-50B4 CG30100 53B1-53B1 CG17725 55D3-55D3 CG5469 55E5-55E5 CG33786/CG33785b 57A8-57A9 CG9865a (uORF1) 57F7-57F7 CG9865a (uORF2) 57F7-57F7 CG9865a (uORF3) 57F7-57F7 CG9878 57F8-57F8 CG30290 57F8-57F9 CG12016 63D1-63D1 CG32573 14F5-14F5 CG11989 67D2-67D2 CG7869 68A4-68A4 CG7628 68A7-68A8 CG9666 76A3-76A3 CG2128 83A4-83A4 CG9288 87F13-87F13 CG9924 88A3-88A4 CG31241 90F11-90F11 CG31178 93F14-93F14 CG7071/CG34131b 94A6-94A6 CG10238 96C1-96C1 CG5116 96E2-96E2 CG14550 96F10-96F10 CG7950 99D3-99D3 54 41 117 90 179 134 73 44 85 20 21 44 48 50 150 48 31 86 21 70 27 121 108 65 84 76 65 94 81 109 50 68 18 129 38 80 25 178 40 157 90 15 111 111 BMC Genomics 2008, 9:61 http://www.biomedcentral.com/1471-2164/9/61 Table 2: Cytological distribution and peptide length of putative CPuORFs in Drosophila melanogaster Flybase transcript identifier and uORF number (FBtrXXXXX_#) CG identifier Cytological gene location uORF length (a.a.) a Gene with multiple CPuORFs in the same 5'UTR b Different gene identifiers annotated as producing the same transcript; the first CG identifier predicts the translation of the mORF and the second CG identifier predicts the translation of the uORF. essentially unchanged under these restrictions (mean of 39 amino acids ± 13), whereas the distribution of Dro- sophila uORFs peaks at an even greater length, 81–100 amino acids (mean of 92 amino acids ± 29; Figure 1C). Longer uORF lengths in Drosophila may reflect a need for stronger suppression of mORF translation than in plants, consistent with the observations of the above-mentioned cell culture studies. Alternatively, insect cells may exhibit more efficient reinitiation resulting in a requirement for longer uORFs to attenuate mORF translation. Physical mapping reveals clustering of CPuORFs independently of gene duplication In insect and mammalian genomes, clusters of closely related genes can sometimes occur, such as the Hox gene clusters [36]. To determine whether genes with uORFs Page 5 of 14 (page number not for citation purposes)