Dixon J E, Andrews P C
Adv Exp Med Biol. 1985;188:19-29. doi: 10.1007/978-1-4615-7886-4_2.
Pancreatic tissue of the channel catfish (Ictalurus punctatus) contains two somatostatins. The amino acid sequence of a 14-residue containing peptide (SS-14) is identical in sequence and has the same mass ion by fast atom bombardment mass spectrometry as mammalian SS-14. A 22-residue somatostatin (SS-22) has also been isolated and its amino acid sequence determined. The amino acid sequence differs from that reported by Oyama et al. (J Biol Chem 255:2251, 1980) in two of the 22-residues (positions 5 and 19). Somatostatin-22 is a glycoprotein, with carbohydrate attached at Thr-5. Several 22-residue peptides have been purified and all of them have identical amino acid compositions and different carbohydrate structure and/or composition. SS-22 has 7 amino acid residues which are identical to those observed in SS-14. The nucleotide sequence of the two cDNAs coding for SS-14 and SS-22 have been determined. The mRNAs encode precursors to SS-14 and SS-22 of 114 and 105 residues, respectively. The two precursors also have different amino acid sequence at the site of prohormone proteolytic processing. Analysis of genomic DNA reveals that SS-14 and SS-22 sequences are present on different restriction fragments and thus are encoded by separate genes.
斑点叉尾鮰（Ictalurus punctatus）的胰腺组织含有两种生长抑素。一种含14个氨基酸残基的肽（SS - 14）的氨基酸序列在顺序上与哺乳动物的SS - 14相同，并且通过快原子轰击质谱法测得的质量离子也相同。一种含22个氨基酸残基的生长抑素（SS - 22）也已被分离出来并确定了其氨基酸序列。该氨基酸序列在22个残基中的两个位置（第5位和第19位）与Oyama等人（《生物化学杂志》255:2251，1980）报道的不同。生长抑素 - 22是一种糖蛋白，在苏氨酸 - 5处连接有碳水化合物。几种含22个氨基酸残基的肽已被纯化，并且它们都具有相同的氨基酸组成以及不同的碳水化合物结构和/或组成。SS - 22有7个氨基酸残基与在SS - 14中观察到的相同。编码SS - 14和SS - 22的两个cDNA的核苷酸序列已被确定。这些mRNA分别编码114个和105个残基的SS - 14和SS - 2
