products across the rough endoplamic reticulum The leader peptide is cleaved and removed before the antibody molecule is secreted.The V segment encodes the first 95terminal amin acids of the Vregion of the antibody Lchain.TheJsegent conist of five alternative forms encode the remaining 12 or more amino acids of B region of the L chains.All segment are separated by short introns.In contrast,the single C region is preceded by a long intervening sequence. Recognition Signals for V-J joining Analysis of DNA sequence has revealed that a set of conserve nucleotides border ents.These sequences of DNA occur at the site where B-J fusior joining process After each V segment is a heptamer (7)with identical sequence (5'CACAGTG 3"), followed by a spacer of 11 or 12 nucleotides of unconserved sequence.The spacer is followed by a nonanucleotide (9)(5'ACAAAAACC3'),or its analogue.Preceding the J segments there are two signal sequence complementary to those following the B segments. The fir st is n cleotide (5'GGTTTTTTGT3')o curs. of 23 or 24 nucletides,hich is followed by the heptanucletide(CACG).When two segments can join,one always has a 11 or 12 nucleotide-long spacer between its conserved heptanucleotide and nonanucleotide,while the other has a 23 or 24 Nonmer 110r12 Nucleotides nucleotide-long spacer products across the rough endoplamic reticulum The leader peptide is cleaved and removed before the antibody molecule is secreted. The V segment encodes the first 95 N-terminal amino acids of the V region of the antibody L chain. The J segment consist of five alternative forms encode the remaining 12 or more amino acids of B region of the L chains. All segment are separated by short introns. In contrast, the single C region is preceded by a long intervening sequence. Recognition Signals for V-J joining Analysis of DNA sequence has revealed that a set of conserve nucleotides border germline B and J segments. These sequences of DNA occur at the site where B-J fusion takes place and may provide recognition signals to facilitate the joining process. After each V segment is a heptamer (7) with identical sequence (5'CACAGTG 3"), followed by a spacer of 11 or 12 nucleotides of unconserved sequence. The spacer is followed by a nonanucleotide (9) (5'ACAAAAACC3'), or its analogue. Preceding the J segments there are two signal sequence complementary to those following the B segments. The first is nonanucleotide (5'GGTTTTTTGT3') occurs, then a spacer of 23 or 24 nucleotides, which is followed by the heptanucleotide (5'CACTGTG3'). When two segments can join, one always has a 11 or 12 nucleotide-long spacer between its conserved heptanucleotide and nonanucleotide, while the other has a 23 or 24 nucleotide-long spacer