May bind to bacterial LPS and thus specifically inhibit the LPS-mediated activation of the hemolymph coagulation. It has a strong antibacterial effect especially on the growth of Gram-negative bacteria (By similarity). Isoform 1 is highly expressed in muscle and stomach, moderately in heart and gill and at lower levels in hemocytes and hepatopancreas. Isoform 2 is mainly expressed in gill, hepatopancreas, muscle and eyestalk. By injection with live V.alginolyticus. Isoform 2 expression is highest 24 hours post-injection. Expression of isoform 1 and isoform 2 is reduced at 3 hours post-injection, increases to a peak at 12 hours post-injection, and returns to control levels at 32 hours post-injection (PubMed:21168510). Isoform 1 expression is up-regulated at 3 and 24 hours post-injection and reaches a peak at 48 hours post-injection (PubMed:20167286). Major isoform. Minor isoform detected in approximately 30% of the cDNA clones. May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay.