Somewhat ambguous- hydropathy, hydro-moment plot might help.
N-term in insects and nematodes is OK
In some may be leader peptide.

Asuumx3       MLSAVRRAIPLSARILRTSLIQRCAGA
Celegans      MAASLRHMAHFQKALLVA
Asperg.o. MASIARQSSLLRQSCLSAFRSPFATRNGAGVSQVVAFHA
                                               10        20        30   
                  |         |         |         |     *   |         |
Humanx2      --------------------------SGSKAASLHWTSERVVSVLLLGLLPAAYLNP 
QPSbov       --------------------------SGSKAASLHWTGERVVSVLLLGLIPAAYLNP 
Gallus       --------------------------GSSKAASLHWTSERAVSALLLGLLPAAYLYP 
Droso        ---PLAVAKIVAPVVREISVSAPRMASAGSSHTLLWTVERIVSAGLLAVIPAAFIAP
Asuumx3      ----TSAAVTGAAPPQFDPIAAEKGFKPLHSHGTLFKIERYFAAAMVPLIPAAYFIH
Celegans     ---RSAPRISTIVRATSTLNDGNDGASKVPDHSMHFKLERLWAVGMLPILPASYFIH
Sacchcere    LTIPFLPVLPQKPGGVRGTPNDAYVPPPENKLSYHWYMEKIFALSVVPLATTAMLTTGPL 
Asperg.o.    SAKKQILPPLPQTIQGTMNDPAPIPTPHPSEGSYHWTFERAISAGLVPLTIAPFAAG
Chondrus                                   MITFQWLIVRVVALFISLTILIDI
Porphyra                  MYKTLLAQVFFHSIAKKKLYFFWL-PRLFSLLLVPGFLFDI
S.lycopersicum                MKEGISGLRNESSKTKRTGLFQRITAAFLLPLIIIYK 
Rrubrum                   MSLRSPLGRARRGFRQGGAANHWMAERLPAIALVPLALWFVFV--
Reclinomonas                   MTEKLLHFIRTKSGSMHWWLQRFLAILLAPIILYLLFD
parden                   MRYITPRKAAEGLGSAHEGTQHHWAMTVSAVALTVLTPLFMIVV 
Brady            MSATDTPKRSMRTPLGRVRNLGAAHSGTSDFWRQRITGVAMVLMMIPVIVI---
EcoliSDH     --------------------MVSNASALGRNGVHDFILVRATAIVLTLYIIYMVGEGF 
Woli                MTNESILESYSGVTPERKKSRMPAKLDWWQSATGLFLGLFMIGHMFFVSTILL ???
                                           TMHelix 1

            30                             40        50        60       
  |          |                              |    *    |     **  |         
Humanx2      ----------------------CSAMDYSLAAALTLHGHWGLGQVVTDYVH
QPSbov       ----------------------CSAMDYSLAATLTLHSHWGIGQVVTDYVH
Gallus       ----------------------GPAVDYSLAAALTLHGHWGLGQVITDYVH
Droso       -----------------------SQVLDALMAISVVIHTHWGVEAMVVDYMR
Asuumx3      ----------------------GREMDLCLALALTLHVHWGVWGVVNDYGR
Celegans     ----------------------GPVMDAVLTVALTLHIHWGIHGVVYDYAR
Sacchcere    ----------------------STAADSFFSVMLLGYCYMEFNSCITDYIS  
Asperg.o     -------------  -------SLNMDAVLCSFIVLHSHIGFQAAIIDYFP
Chondrus     ------------------------EMFVVMLSFLIIHISIGLKAIIHDYIH
Porphyra     --(bact linker helix)---EILFLFHPIILLHASLGLSVIIEDYIH
S.lycopersicum                     KVSSTFLLNLSLFWHINEGIEEIMADYVH
Rrubrum       AIISNLGASYAQIQAFMAVPLNATLMLLTVFCAFFHGALGLIVIIEDYVQ
Reclinomona VAIYIGQQSDPTVMMFLNRIFNHNSIFIFITSVILIWHVRGGMEVIIEDYVH
parden       ARAIGLSQEQLLAYFGRPFPALITA---LFVIVGMVHFIKGTRIMIDDYFQ--
Bradyx9        IVMLFGRNQAFVAQTIGSLPIAIIMLLFIFASAWHMKIGMQVVIEDYVH
EcoliSDH     PVFATSGELTYEVWIGFFASAFTKVFTLLALFSILIHAWIGMWQVLTDYVK
Woli      GDNVMLWVTKKFELDFIFEGGKPIVVSFLAAFVFAVFIAHAFLAMRKFPINYRQY 
              bact linker helix            TMHelix 2

             70        80        90       100      110
                        |         |         |        |
Humanx2      ---GDALQKAAKAGLLALSALTFAGLCYFNYHDVGICKAVAMLWKL
QPSbov       ---GDAVQKAAKTGLLVLSAFTFAGLCYFNYHDVGICKAVAMLWKL
Gallus       ---GDTPIKVANTGLYVLSAITFTGLCYFNYYDVGICKAVAMLWSI  TGL:G82 pocket where C:L61 inserts
Droso       PSVVGNVLPKVAHIALIIISVATLGGLFYFIQNDVGLANGIKRFWAIKGKDAEKA
Asuumx3     PFVLGDTLAAAVRVGAYIFTACLLAGLLYFNEHDVGLTRAFEMVWEL---
Celegans    PYVIGEAAAKAAHVGVYLITGLLLGALLHFNTNDVGITKAFELVFSL---
Sacchcere    ERVYGVWHKYAMYMLGLGSAVSLFGIYKLETENDGVVGLVKSLWDSSEKDNSQKIEAKK
Asperg.o.    TRRVPKTATFCNWLLRAFTLTTAVGLYEFETNDVGVTEAFKRVWKA 
Chondrus        FQKIKLMLLILLRVSAIEISRSFRTFYIIIKNT--
Porphyra        IETIKFQYLSLIKLLLVLLINLNILYLL---
S.lycopersicum  QEMTRNWILVYLRLFLLIVIKDVFLSLVFFLKKK 
Rrubrum         NHAVKNALVFGTKLYALFGAVLAAVSILKLTFGG
Reclinomonas    GEKTRIVSIFLIRVIAIEIMEYLYKCSIIF-----
paradeni        GGTRKVAIIFSVIFGWAVIAAAVYALARMGLGAIVVL
Bradyx9         NEKLKLTAIMLNNFFSIAVALASTYAILKLSSGV
EcoliSDH     ---PLALRLMLQLVIVVALVVYVIYGFVVVWG             based on structure
Woli            LTF<helix 3 omitted> 
                   TMHelix 3                     Vert CTHelix
                -------------------------------  ----------

Here we are aligning SDHD with the first two helices of wolinella FRD, 
because thats what the structure aligns (and SDHC with last 3) but there is no real homolgy
[Paracoccus denitrificans]
MRYITPRKAAEGLGSAHEGTQHHWAMTVSAVALTVLTPLFMIVVARAIGLSQEQLLAYFGRPFPALITAL
FVIVGMVHFIKGTRIMIDDYFQGGTRKVAIIFSVIFGWAVIAAAVYALARMGLGAIVVL

Aspergg.o SDHD AB449815: D124E
        10         20         30         40         50         60 
MASIARQSSL LRQSCLSAFR SPFATRNGAG VSQVVAFHAS AKKQILPPLP QTIQGTMNDP 
APIPTPHPSE GSYHWTFERA ISAGLVPLTI APFAAGSLNP VMDAVLCSFI VLHSHIGFQA 
AIIeYFPTRR VPKTATFCNW LLRAFTLTTA VGLYEFETND VGVTEAFKRV WKA 

-structural alignment of SDHD: 3d tmh is offset, but pretty clear D62-D88    DTP-NY
                                                            E.col D87 D113   LAL-VW
  and this seems to ext back to 32, 57 (but with displacement in the 2-3 linker GPA/AKV

>NP_054431.1 succinate dehydrogenase subunit 4 (mitochondrion) [Marchantia paleacea]
MKTHRETLGHWLLQRITAAFLIPTILIANVSTLILLNILLFWHIHVGIEEILADYVHHEVTRNWILILLR
VFCLIIIKYVFVFFVF


 1 Human        129 
 2 bovine       129 
 3 Gallus       129 
 4 EcoliSDH     129 
 1    --    --    --    M1    
 2    --    --    --    V2    
 3    --    --    --    S3    
 4    --    --    --    N4    
 5    --    --    --    A5    
 6    --    --    --    S6    
 7    S1    S1    G1    A7    
 8    G2    G2    S2    L8    
 9    S3    S3    S3    G9    
 10   K4    K4    K4    R10   
 11   A5    A5    A5    N11   
 12   A6    A6    A6    G12   
 13   S7    S7    S7    V13   
 14   L8    L8    L8    H14   
 15   H9    H9    H9    D15   
 16   W10   W10   W10   F16   
 17   T11   T11   T11   I17   
 18   S12   G12   S12   L18   
 19   E13   E13   E13   V19   
 20   R14   R14   R14   R20   
 21   V15   V15   A15   A21   
 22   V16   V16   V16   T22   
 23   S17   S17   S17   A23   
 24   V18   V18   A18   I24   
 25   L19   L19   L19   V25   
 26   L20   L20   L20   L26   
 27   L21   L21   L21   T27   
 28   G22   G22   G22   L28   
 29   L23   L23   L23   Y29   
 30   L24   I24   L24   I30   
 31   P25   P25   P25   I31   
 32   A26   A26   A26   Y32   
 33   A27   A27   A27   M33   
 34   Y28   Y28   Y28   V34   
 35   L29   L29   L29   G35   
 36   N30   N30   Y30   F36   *
 37   P31   P31   P31   F37   *
 38   C32   C32   G32   A38   *
 39   --    --    --    T39   
 40   --    --    --    S40   
 41   --    --    --    G41   
 42   --    --    --    E42   
 43   --    --    --    L43   
 44   --    --    --    T44   
 45   --    --    --    Y45   
 46   --    --    --    E46   
 47   --    --    --    V47   
 48   --    --    --    W48   
 49   --    --    --    I49   
 50   --    --    --    G50   
 51   --    --    --    F51   
 52   --    --    --    F52   
 53   --    --    --    A53   
 54   --    --    --    S54   
 55   --    --    --    A55   
 56   --    --    --    F56   
 57   --    --    --    T57   
 58   S33   S33   P33   K58   *Shenoy&Yu 
 59   A34   A34   A34   V59   *AzidoQ-labeled
 60   M35   M35   V35   F60   *peptide at
 61   D36   D36   D36   T61   *distal site.
 62   Y37   Y37   Y37   L62   *
 63   S38   S38   S38   L63   
 64   L39   L39   L39   A64   
 65   A40   A40   A40   L65   
 66   A41   A41   A41   F66   
 67   A42   T42   A42   S67   
 68   L43   L43   L43   I68   
 69   T44   T44   T44   L69   
 70   L45   L45   L45   I70   
 71   H46   H46   H46   H71  Heme Ligand 
 72   G47   S47   G47   A72   
 73   H48   H48   H48   W73   
 74   W49   W49   W49   I74   
 75   G50   G50   G50   G75   
 76   L51   I51   L51   M76   
 77   G52   G52   G52   W77   
 78   Q53   Q53   Q53   Q78   
 79   V54   V54   V54   V79   
 80   V55   V55   I55   L80   
 81   T56   T56   T56   T81   
 82   D57   D57   D57   D82  D88 in paradeni- carboxin resist. 
 83   Y58   Y58   Y58   Y83  Quinone Ligand 
 84   V59   V59   V59   V84   
 85   H60   H60   H60   K85   
 86   G61   G61   G61   P86   
 87   D62   D62   D62   L87   
 88   A63   A63   T63   A88   
 89   L64   V64   P64   L89   
 90   Q65   Q65   I65   R90   
 91   K66   K66   K66   L91   
 92   A67   A67   V67   M92   
 93   A68   A68   A68   L93   
 94   K69   K69   N69   Q94   
 95   A70   T70   T70   L95   
 96   G71   G71   G71   V96   
 97   L72   L72   L72   I97   
 98   L73   L73   Y73   V98   
 99   A74   V74   V74   V99   
 100  L75   L75   L75   A100  
 101  S76   S76   S76   L101  
 102  A77   A77   A77   V102  
 103  L78   F78   I78   V103  
 104  T79   T79   T79   Y104  
 105  F80   F80   F80   V105  
 106  A81   A81   T81   I106  
 107  G82   G82   G82   Y107  
 108  L83   L83   L83   G108  
 109  C84   C84   C84   F109  
 110  Y85   Y85   Y85   V110  
 111  F86   F86   F86   V111  
 112  N87   N87   N87   V112  
 113  Y88   Y88   Y88   W113  
 114  H89   H89   Y89   G114  
 115  D90   D90   D90   V115  
 116  V91   V91   V91   --    
 117  G92   G92   G92   --    
 118  I93   I93   I93   --    
 119  C94   C94   C94   --    
 120  K95   K95   K95   --    
 121  A96   A96   A96   --    
 122  V97   V97   V97   --    
 123  A98   A98   A98   --    
 124  M99   M99   M99   --    
 125  L100  L100  L100  --    
 126  W101  W101  W101  --    
 127  K102  K102  S102  --    
 128  L103  L103  I103  --    
 129   104   104   104   116  
>Human       
------SGSKAASLHWTSERVVSVLLLGLLPAAYLNPC-------------------SAMD
YSLAAALTLHGHWGLGQVVTDYVHGDALQKAAKAGLLALSALTFAGLCYFNYHDVGICKAVAMLWKL
>bovine      
------SGSKAASLHWTGERVVSVLLLGLIPAAYLNPC-------------------SAMD
YSLAATLTLHSHWGIGQVVTDYVHGDAVQKAAKTGLLVLSAFTFAGLCYFNYHDVGICKAVAMLWKL
>Gallus      
------GSSKAASLHWTSERAVSALLLGLLPAAYLYPG-------------------PAVD
YSLAAALTLHGHWGLGQVITDYVHGDTPIKVANTGLYVLSAITFTGLCYFNYYDVGICKAVAMLWSI
>EcoliSDH    
MVSNASALGRNGVHDFILVRATAIVLTLYIIYMVGFFATSGELTYEVWIGFFASAFTKVFT
LLALFSILIHAWIGMWQVLTDYVKPLALRLMLQLVIVVALVVYVIYGFVVVWGV-------------




>Human       
----------------------------------SGSK
AASLHWTSERVVSVLLLGLLPAAYLNPCSAMDYSLAAALTLHGHWGLGQVVTDYVHGDAL
QKAAKAGLLALSALTFAGLCYFNYHDVGICKAVAMLWKL
>bovine   
----------------------------------SGSK
AASLHWTGERVVSVLLLGLIPAAYLNPCSAMDYSLAATLTLHSHWGIGQVVTDYVHGDAV
QKAAKTGLLVLSAFTFAGLCYFNYHDVGICKAVAMLWKL
>Gallus       
----------------------------------GSSK
AASLHWTSERAVSALLLGLLPAAYLYPGPAVDYSLAAALTLHGHWGLGQVITDYVHGDTP
IKVANTGLYVLSAITFTGLCYFNYYDVGICKAVAMLWSI
>EcoliSDH    
MVSNASALGRNGVHDFILVRATAIVLTLYIIYMVG--
---FFATSGELTYEVWIGFFASAFT---KVFTLLALFSILIHAWIGMWQVLTDYVKPLAL
R-------LMLQLVIVVALVVY------VIYGFVVVWGV

Asperg.o SDHD AB449815: D124E
        10         20         30         40         50         60 
MASIARQSSL LRQSCLSAFR SPFATRNGAG VSQVVAFHAS AKKQILPPLP QTIQGTMNDP 
APIPTPHPSE GSYHWTFERA ISAGLVPLTI APFAAGSLNP VMDAVLCSFI VLHSHIGFQA 
AIIeYFPTRR VPKTATFCNW LLRAFTLTTA VGLYEFETND VGVTEAFKRV WKA