Unique hexokinase messenger ribonucleic acids lacking the porin-binding domain are developmentally expressed in mouse spermatogenic cells.
We have identified cDNAs representing three hexokinase mRNAs (Hk1-sa, Hk1-sb, Hk1-sc) by screening mouse spermatogenic cell cDNA libraries with a mouse hepatoma cell line hexokinase (Hk1) cDNA [Arora KK, Fanciulli M, Pederson PL. J Biol Chem 1990; 265:6481-6488]. Although all three cDNAs show 99% identity to the somatic Hk1 cDNA sequence throughout most of their coding region, they differ from this sequence at the 5' end. They contain a common spermatogenic cell-specific sequence and a sequence unique to each cDNA immediately 5' to the common domain. However, they lack the porin-binding domain (PBD) present in this region of Hk1, used for binding to a pore-forming protein in the outer mitochondrial membrane. These observations appear to support a model proposed by others for hexokinase gene evolution in mammals. In addition, we found that Hk1-sb has an internal sequence that is not present in Hk1, Hk1-sa, or Hk1-sc. Moreover, Hk1-sa and Hk1-sb transcripts are developmentally expressed in mouse spermatogenic cells. Hk1-sa mRNA is first expressed during meiosis and continues to be present in postmeiotic germ cells, while the more abundant Hk1-sb mRNA is detected only in postmeiotic germ cells. These and other findings suggest that enzymes encoded by Hk1-sa, Hk1-sb, and Hk1-sc are present only in spermatogenic cells.
Gamete Biology Section, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709.
C
C
Mori
J E
JE
Welch
K D
KD
Fulcher
D A
DA
O'Brien
E M
EM
Eddy
D000375:Aging; D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D015152:Blotting, Northern; D004247:DNA / Q000737:chemistry / Q000302:isolation & purification; D015870:Gene Expression; D006593:Hexokinase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D017403:In Situ Hybridization; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D018272:Porins; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics*; D013087:Spermatids / Q000201:enzymology; D013090:Spermatocytes / Q000201:enzymology; D013094:Spermatozoa / Q000201:enzymology*; D013737:Testis / Q000737:chemistry / Q000254:growth & development*
D001425:Bacterial Outer Membrane Proteins; D018272:Porins; D012333:RNA, Messenger; D004247:DNA; D006593:Hexokinase