Leishmanolysin (EC 3.4.24.36) (gp63) is a zincmetalloprotease (ND Rawlings et al. 1995 Meth-ods Enzymol 248 : 183-228) abundantly expressedin the promastigote form of Leishmania parasites,where it is attached to the plasma membrane by aglycosylphosphatidylinositol (GPI) anchor (PSchneider et al. 1990 J Biol Chem 265: 16955-16964, TJ Salvatore et al. 1992 Annu Rev Microbiol46 : 65-94). It has been suggested that gp63 be-comes active at multiple steps during the processof macrophage invasion and its function seems tobe required for the parasite’s intraphagolysosomalsurvival (GD Rusell et al. 1989 Immunol Today10: 328-333, AR Miller et al. 1990 Mol BiochemParasitol 39: 267-274, A Brittingham et al. 1996J Immunol 155 : 3102-3111). The protein is encodedby genes present in multiple copies that are clus-tered in two to three tandem repeats usually lo-cated on a single chromosome (JR Webb et al. 1991Mol Biochem Parasitol 48 : 173-184, T Hanekempet al. 1991 Mol Biochem Parasitol 48 : 27-38) andwhich are highly conserved throughout the genus(LL Button et al. 1988 J Exp Med 167: 724-729,HB Steinkraus 1993 Mol Biochem Parasitol 62:173-186, SC Roberts et al. 1993 Mol BiochemParasitol 62 : 157-172, E Medina-Acosta et al. 1993Mol Biochem Parasitol 57: 31-46).The gp63 familiy is constituted by a group ofproteins with different molecular weights depend-ing upon the species. The importance of the majorsurface glycoprotein of Leishmania promastigotes,gp63, in the binding of promastigotes to macroph-ages has been inferred largely due to its abundance,surface localization, and proteolytic activity (JBouvier et al. 1985 J Biol Chem 260 : 15504-15509,R Etges et al. 1986 J Biol Chem 261: 9098-9101,CS Chang 1986 Proc Natl Acad Sci USA 83 : 100-104, Brittingham loc. cit.).In the present work, we report for the first timethe molecular characterization of gp63 gene in L.panamensis, which is the most prevalent Leishma-nia species in Colombia, and also the presence ofcopies containing deletions of this gene either oncDNA or DNA material.In order to identify the gp63 gene from L.panamensis, an internal 940 bp long probe wasgenerated by PCR, using two consensus primersdesigned from the alignment of all Leishmaniagp63 nucleotide sequences reported to date. Lpan1:5’TACGTCGCCTCGGTGCCGA3’ and Lpan2:5´GCACCTGGACGCTGTACG3’ primers weresynthesized by the solid phase phosphito-triestermethod. This probe (U62634) was radiolabelledand used for hybridization assays and libraryscreening.A cDNA library was constructed from L.panamensis infective clone M/HOM/PA/71/LS/74stationary phase promastigotes. cDNA was syn-thesized using a cDNA synthesis kit (Amersham)and ligated into the Eco RI site of bacteriophageλgt11. Several clones were isolated and sequencedeither by manual (Sequenase v.2.0; United StatesBiochemical) or automatic (Applied Biosystems373; Perkin Elmer) sequencing using both DNAstrands. Of those, Lp63c1, represents a 2648-ntlong cDNA sequence that is homologous to othergp63 sequences and includes the 1728 nucleotidescoding region, 79 nt of the 5’ untranslated region,and 841 nt of the 3’ untranslated region (Figure).However, this clone exhibits a 44 bp deletion 26 ntdownstream to the start codon causing a frame-shift compared to other previously described gp63genes from Leishmania spp.In order to detect the presence of this gp63 formin L. panamensis genome, we built a Sal I genomiclibrary containing restriction fragments rangingfrom 2.8-3.2 kb in size into the pMOS vector