This CCDS representation uses a downstream start codon, which is more consistent with the presence of an N-terminal signal peptide, and with experimental evidence for cleavage of this signal peptide in PMID:15340161. It should be noted that an alternative upstream start codon, which would result in a protein that is 38 aa longer at the N-terminus, also exists. However, the use of the upstream start codon would eliminate the signal peptide, and it has a weak Kozak signal, so it is likely that leaky scanning by ribosomes will allow the use of the downstream start codon.