hOLF44, a secreted glycoprotein with distinct expression pattern, belongs to an uncharacterized olfactomedin-like subfamily newly identified by phylogenetic analysis.
Secreted proteins are indispensable for the development and differentiation of multicellular organisms. Cloning and characterization of novel or hypothetical genes encoding these proteins are therefore inviting great incentives. Using bioinformatics tools and experimental approaches, we isolated and characterized a human secreted glycoprotein, hOLF44, which contains a highly conserved olfactomedin-like (OLF) domain in the C-terminal. However, phylogenetic analysis revealed that hOLF44 is not clustered into any of the OLF subfamilies containing characterized members, and obviously falls into a newly identified uncharacterized OLF subfamily. Western blot analysis showed that hOLF44 protein is robustly secreted from the transfected COS-7 cells. Expression levels of hOLF44 mRNA are abundant in placenta, moderate in liver and heart, whereas fairly weak in other tissues examined. Immunohistochemical study on human term placenta demonstrated that hOLF44 is mainly localized extracellularly surrounding the syncytiotrophoblastic cells and very rarely expressed in the maternal decidua layer. These results suggest that hOLF44 may have matrix-related function involved in human placental and embryonic development, or play a similar role in other physiological processes. The further functional characterization of hOLF44 may provide insights into a better understanding of the newly identified OLF subfamily.
Zeng
Ling-Chun
LC
Health Science Center, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Second Medical University, 225 South Chongqing Road, Shanghai 200025, China.
Liu
Feng
F
Zhang
Xin
X
Zhu
Zhi-Dong
ZD
Wang
Zhi-Qin
ZQ
Han
Ze-Guang
ZG
Ma
Wei-Jun
WJ
D000595:Amino Acid Sequence; D000818:Animals; D002645:Chickens; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004622:Embryo, Mammalian / Q000502:physiology; D004625:Embryo, Nonmammalian; D016326:Extracellular Matrix Proteins / Q000145:classification* / Q000235:genetics; D005260:Female; D006023:Glycoproteins / Q000145:classification* / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D010920:Placenta / Q000502:physiology; D011247:Pregnancy; D014176:Protein Biosynthesis / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000145:classification; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic / Q000235:genetics; D014162:Transfection; D036341:Intercellular Signaling Peptides and Proteins
D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D011994:Recombinant Proteins; C488965:OLFML3 protein, human; D036341:Intercellular Signaling Peptides and Proteins; C081451:olfactomedin