PLAC4 GI:121949815 placenta-specific 4 1 mkellrlkhc khlltthvhs pwtpsltltp slltldtlth prhrhsspwt 50 51 phsapwtpsl tldtfthpdt lthpghphsp wipslltldt lthpgyphss 100 101 pwtlsltltp siltldsltp hpglphsspw tpsllildtl tqpghphssp 150