Human CCL1 was initially identified by subtractive hybridization as a transcript that was present in a gamma / delta T cell line but not in EBV-transformed B cells. Human CCL1 has been assumed to be a homologue of the mouse TCA3. While the two proteins share only approximately 42% amino acid sequence identity, both chemokines contain an extra pair of cysteine residues not found in most other chemokines. Human CCL1 and mouse TCA3 also share significant sequence homology in the 5’ flanking region of their genes.
CCL1 cDNA encodes a 96 amino acid residue precursor protein with a hydrophobic signal peptide that is cleaved to yield a 73 amino acid residue mature protein. The CCL1 sequence contains one potential N-linked glycosylation site and natural CCL1 secreted by activated T cells is a glycoprotein doublet of 15‑16 kDa. The amino acid sequence of CCL1 identified the protein as a member of the chemokine beta subfamily.
