Cloning and characterization of a novel intronless lactate dehydrogenase gene in human testis.

Using cDNA microarray hybridization from a human testicular cDNA library, one gene named lactate dehydrogenase A-like gene (LDHL, also known as LDHL6B) was cloned. LDHL exhibited 3.8-fold difference at expression level between adult and fetal human testes. The full cDNA length of LDHL is 1680 bp and had a 1145 bp open reading frame, which encoded a 41.9 kDa protein of 381 amino acids. Sequence analysis showed that LDHL harbors all the domains (one lactate/malate dehydrogenase, NAD binding domain and one lactate/malate dehydrogenase, alpha/beta C-terminal domain) in lactate dehydrogenase gene family. Blasting human genome database localized LDHL to human chromosome 15q22.2 and it was an intronless gene. Results of multiple-tissue PCR and real-time PCR showed that LDHL expressed mainly in testis and its mRNA abundance was testis development-related. In summary, LDHL is believed to be involved in testis development and spermatogenesis.